Nuclear Magnetic Resonance
The Virginia Tech NMR Facility operates high-field superconducting magnets ranging from 400-600 MHz for cutting-edge research in chemistry, materials science, and related fields. Our facility provides state-of-the-art instrumentation with comprehensive user training and support.
| Hourly rate | Internal | Federal | External | Expedited |
|---|---|---|---|---|
| Instrument Time | $9.90 | $15.90 | $125.00 | $187.25 |
| Tech Assist | $40.00 | $64.40 | $125.00 | --- |
Medical Devices & Implants
STOP: If you have any of the following, you MUST get staff clearance before entering:
- Cardiac pacemakers or ICDs
- Cochlear implants
- Neurostimulators (deep brain, spinal cord, vagus nerve)
- Aneurysm clips
- Metallic foreign bodies (shrapnel, metal fragments)
"MRI Safe" ≠ "NMR Safe" — Our magnets operate at much higher fields (9.4-14.1 Tesla) than clinical MRI (1.5-3.0 Tesla)
DANGER: Magnetic Field Hazards
The danger of the magnetic field is proportional to the size of an object:
Projectile Hazard (Heavy Items): Heavy metal objects like large metal carts or heavy tools must NEVER cross the 5 Gauss line marked around each magnet, as they will become dangerous projectiles. Gas cylinders are absolutely prohibited without explicit staff authorization.
Equipment Hazard (Small Items): Items like paper clips or bobby pins are attracted when very close to the magnet. Although they won't become projectiles, small items can get pulled onto the magnet unnoticed and interfere with the shims.
- Submit training request via email facility staff
- Complete general facility training covering:
- Safety protocols and hazards
- Sample preparation essentials
- Instrument operation and queues
- Accessing your data
- Receive shared group credentials for:
- Instrument login
- LOGS data access
- FACES scheduling system
- Door code access (provided with facility training)
Additional training required for:
- Variable Temperature (VT) experiments (-40°C to +135°C)
- Diffusion/DOSY measurements
- Solid-State MAS (4mm Rotor)
- Advanced Water Suppression techniques
- Quantitative NMR
- EPR (Electron Paramagnetic Resonance)
Safety Policies
Critical Safety Rules
- Remove mechanical watches before approaching magnet during sample insertion:
- Mechanical watches will be permanently magnetized and ruined
- Piercings and jewelry are generally safe, but take care if large and ferromagnetic
- NMR tube transport: Always use secondary containment (no glass containers)
- Magnet quench: If you hear loud roar/boom or see dense fog, leave immediately and contact NMR staff
- Report all incidents: Spills, breakage, instrument issues, or safety concerns immediately
- Emergencies: For urgent safety issues (quench, injury, fire, significant chemical spills) — especially outside normal business hours or on weekends — contact NMR staff by phone immediately at 540-267-6502. Do not wait for an email reply in an emergency.
- Never work alone if handling potentially hazardous samples
- Know the location of emergency exits and safety equipment
- Keep your phone accessible for emergency communication
- If a magnet quench or safety incident occurs, evacuate immediately and contact NMR staff
Do NOT use chipped, cracked, or damaged NMR tubes.
Damaged tubes can:
- Cause instrument downtime and costly probe damage
- Get stuck in the magnet or autosampler
- Produce poor quality spectra
Tube Retirement Guidelines:
- Chips or cracks: Any visible damage — retire immediately
- Heavy scratches: Deep scratches affect spinning and shimming
- Bent tubes: Even slight bends cause problems
- Multiple uses: Disposable tubes should generally be used 1-3 times maximum
- Never oven-dry economy tubes; heating deforms the glass and causes autosampler/probe strikes
Console & Field Strength: Bruker Avance Neo, 600 MHz (14.1 T)
Probe: 5 mm Prodigy TCI triple-resonance inverse cryoprobe (1H, 13C, 15N with z-gradients)
Best For: Highest 1H sensitivity in the facility. Optimized for 1H-detected inverse correlation experiments (e.g., HSQC, HMBC); direct 13C observe experiments should be directed to the 500 MHz BBO Prodigy systems.
Experimental Section Text (Copy/Paste):
NMR experiments were performed on a Bruker Avance Neo 600 MHz spectrometer equipped with a 5 mm Prodigy TCI (1H, 13C, 15N) cryoprobe and z-axis pulsed-field gradients.
Console & Field Strength: Bruker Avance Neo, 500 MHz (11.7 T)
Probe: 5 mm Prodigy BBO broadband cryoprobe (broadband observation with 1H decoupling/observation and z-gradients)
Primary Use: Primary destination for routine and long 13C and heteronuclear (X-nucleus) work. Cryogenic broadband detection delivers roughly 9–12x the sensitivity of a 400 MHz room-temperature probe, dramatically shortening acquisition times. Walk-up/queued operation.
Experimental Section Text:
NMR spectra were recorded on a Bruker Avance Neo 500 MHz spectrometer equipped with a 5 mm Prodigy BBO cryoprobe and z-axis pulsed-field gradients.
Console & Field Strength: Bruker Avance Neo, 500 MHz (11.7 T)
Probe: 5 mm Prodigy BBO broadband cryoprobe (broadband observation with 1H decoupling/observation and z-gradients)
Primary Use: Scheduled, high-sensitivity 13C and broadband X-nucleus experiments, as well as variable-temperature (VT) studies from -40 °C to +135 °C. Combines cryogenic probe sensitivity with block-time scheduling.
Access & Booking: Reservation-only via FACES (required prior to use); user-adjustable VT requires dedicated VT training and staff approval.
Experimental Section Text:
NMR spectra were recorded on a Bruker Avance Neo 500 MHz spectrometer equipped with an Oxford magnet, a 5 mm Prodigy BBO cryoprobe, and z-axis pulsed-field gradients.
Console & Field Strength: JEOL ECZL400, 400 MHz (9.4 T)
Probe: 5 mm ROYAL HFX probe (tunable 1H, 19F, and broadband X-nuclei with z-gradients)
Primary Use: The facility's primary instrument for 19F NMR, routine 1H screening, and variable-temperature studies (-40 °C to +135 °C). Provides the lowest 19F probe background on-site, superior 1H-19F correlation, and simultaneous two-channel decoupling (e.g., simultaneous 1H and 19F decoupling during 13C acquisition).
Access & Operation: Open-access walk-up operation with run times permitted up to 60 minutes per sample. User-adjustable VT requires dedicated training and staff approval.
Experimental Section Text:
NMR spectra were recorded on a JEOL ECZL400 400 MHz spectrometer equipped with a 5 mm ROYAL HFX probe and z-axis pulsed-field gradients.
Console & Field Strength: Bruker Avance Neo, 400 MHz (9.4 T)
Probe: 5 mm room-temperature broadband iProbe (direct broadband detection with 1H decoupling/observation, automated tuning and matching, and z-gradients)
Primary Use: High-throughput open-access workhorse for fast 1H screening, reaction monitoring, solvent checks, and quick 13C acquisitions on concentrated samples.
Access & Operation: Walk-up autosampler queue with a strict 20-minute maximum limit per sample to maintain rapid queue turnover for all users.
Experimental Section Text:
NMR spectra were recorded on a Bruker Avance Neo 400 MHz spectrometer equipped with a 5 mm room-temperature broadband iProbe and z-axis pulsed-field gradients.
Console & Field Strength: Bruker Avance Neo, 400 MHz (9.4 T)
Supported Probes:
4 mm Solid-State Magic-Angle Spinning (SSNMR MAS) probe
DiffBBI diffusion probe with 60 A gradient amplifier
10 mm BBO large-volume/viscous sample probe
5 mm room-temperature broadband iProbe
Primary Use: Multi-configuration specialty spectrometer dedicated to solid-state NMR (SSNMR), pulsed-field-gradient diffusion NMR (DOSY), and large-volume/viscous polymer samples. Routine 5 mm solution NMR is available only when the system is not configured for specialty experiments.
Access & Requirements: Specialty modes require staff coordination, probe changes, and specialized hardware setups. Initial solid-state and diffusion experiments are run by staff in service mode; independent use requires project validation and specialized training.
Experimental Section Text (Select by configuration):
For Solid-State NMR:
Solid-state NMR spectra were acquired on a Bruker Avance Neo 400 MHz spectrometer equipped with a 4 mm MAS probe.
For Diffusion NMR:
Diffusion NMR experiments were performed on a Bruker Avance Neo 400 MHz spectrometer equipped with a DiffBBI probe and a 60 A pulsed-field-gradient amplifier.
For 10 mm Solution / Polymers:
NMR spectra were recorded on a Bruker Avance Neo 400 MHz spectrometer equipped with a 10 mm BBO probe and z-axis pulsed-field gradients.
For 5 mm Solution NMR:
NMR spectra were recorded on a Bruker Avance Neo 400 MHz spectrometer equipped with a 5 mm room-temperature broadband iProbe and z-axis pulsed-field gradients.
Console & Field Strength: Bruker Avance Neo, 400 MHz (9.4 T)
Probe: DiffBB broadband diffusion probe, along with specialized high-gradient diffusion probe heads
Primary Use: Dedicated pulsed-field-gradient (PFG) and diffusion-ordered spectroscopy (DOSY) system for measuring molecular self-diffusion, transport properties, and ionic mobility in electrolytes, polymers, and complex fluids.
Access & Management: Managed separately by the Madsen Research Group. This is a dedicated research instrument and is not available for general facility walk-up use. Access and collaborative work must be arranged directly through the Madsen Lab.
Experimental Section Text:
Diffusion NMR experiments were performed on a Bruker Avance Neo 400 MHz spectrometer equipped with a DiffBB high-power pulsed-field-gradient diffusion probe.
Routine 1H Screening & Reaction Monitoring
Best choice: Neo400HT or JEOL ECZL400
Application: Fast, routine 1H NMR on concentrated samples, quick reaction monitoring, solvent checks, and preliminary structure verification.
Instrument Limits & Availability: Both are open-access walk-up systems requiring no advance reservation. Neo400HT enforces a strict 20-minute maximum limit per sample to maintain rapid queue turnover. The JEOL ECZL400 accommodates runs up to 60 minutes for slightly more demanding scans.
Access & Requirements: Available immediately to all facility-trained users during regular open-access hours.
Next steps: Load your sample directly into the walk-up carousel on either instrument; reserve our 500 MHz or 600 MHz systems if your sample is dilute or requires longer multi-dimensional experiments.
Best choice: Neo500BBO or Neo500Oxford
Application: Direct detection of 13C and other low-sensitivity heteronuclei (such as 31P, 29Si, 11B, 15N, and transition metals), as well as routine characterization where rapid heteronuclear acquisition is needed.
Probe Capabilities & Speed: Equipped with cryogenic Prodigy BBO probes that provide approximately 9–12x the X-nucleus sensitivity of a standard 400 MHz room-temperature probe. This dramatic gain reduces multi-hour or overnight 1D 13C and broadband acquisitions down to minutes.
Access & Booking: Neo500BBO operates in walk-up/queued mode for quick turnarounds; Neo500Oxford requires advance scheduling via FACES for longer blocks of instrument time.
Next steps: Select either 500 MHz system for your routine or dilute direct heteronuclear experiments following standard facility training.
Best choice: Neo600TCI
Application: Highly dilute solutions, natural products, biomacromolecules, kinetics with trace intermediates, and complex multidimensional experiments (e.g., 2D/3D HSQC, HMBC, NOESY, TOCSY) where proton detection sensitivity is the primary bottleneck.
Probe Capabilities & Focus: Features a triple-resonance inverse cryoprobe (TCI Prodigy) with a cryogenic 1H channel, delivering the highest 1H sensitivity in the facility. Because the heteronuclear coils are outer-mounted and uncooled, this platform is optimized strictly for 1H-detected inverse experiments, not for routine 1H screening of concentrated samples or direct heteronuclear detection (e.g., standard 1D 13C or direct broadband acquisition).
Access & Requirements: Reserved for projects requiring high proton sensitivity or advanced multidimensional experiments. To preserve cryoprobe access for demanding samples, routine high-concentration screening should be run on our 400 MHz or 500 MHz spectrometers.
Next steps: Contact facility staff to discuss experimental feasibility, determine whether your sample requires the 600 MHz cryoprobe, or receive guidance on setting up advanced multidimensional pulse programs.
Best choice: JEOL ECZL400
Application: Fluorinated pharmaceuticals, polymers, catalysts, and complex synthetic intermediates. Equipped with a specialized ROYAL HFX probe that features ultra-low 19F background and superior 1H-19F correlation performance.
Advanced Decoupling Capabilities: Supports simultaneous two-channel decoupling, enabling 13C acquisition with simultaneous 1H and 19F decoupling, as well as routine 1H-decoupled 19F experiments. This eliminates complex multi-nucleus splitting and dramatically simplifies overlapping, crowded spectra.
Access & Requirements: Available for walk-up or scheduled use following standard facility training, with advanced multi-channel experiment templates supported.
Next steps: Contact facility staff if you need assistance setting up advanced multi-nuclear correlation pulse programs or 19F-specific decoupling sequences.
Best choice: JEOL ECZL400 or Neo500Oxford
Application: Temperature-dependent kinetics, dynamic exchange processes, phase transitions, and thermal stability studies from -40 °C to +135 °C.
Access & Requirements: Variable-temperature operation within the -40 °C to +135 °C range requires dedicated VT safety and workflow training, as well as prior staff approval. These two instruments are the only systems authorized for user-adjustable VT control. Any experiments outside this window or involving prolonged extreme temperatures are restricted to staff-only operation.
Next steps: Contact facility staff to discuss your experimental parameters, verify solvent boiling/freezing points and pressure safety, and schedule specialized VT training.
Best choice: Neo400Jack (10 mm BBO) or Neo500BBO
Application: Ideal for viscous solutions, sticky resins, slowly dissolving polymers, or low-solubility samples where a standard 5 mm tube provides insufficient sample mass or poor shimming performance.
Access & Requirements: The 10 mm probe on Neo400Jack requires a staff-scheduled probe change, specialized tuning, and dedicated training for independent use. Routine 5 mm polymer samples should first be considered on our standard broadband solution systems (such as the Neo500BBO).
Next steps: Contact facility staff directly to evaluate sample compatibility, discuss tube requirements, and schedule the necessary probe configuration.
⚠️ Inquiry Required Prior to Scheduling
Diffusion NMR requires specialized probe setup, gradient calibration, and prior sample vetting. Before requesting instrument time or training, please consult the Diffusion NMR Inquiries section located under the Operations menu for sample requirements, gradient limits, and submission details.
Best choice: Neo400Jack (DiffBBI) or Neo400Diff
Application: Diffusion-ordered spectroscopy and pulsed-field-gradient measurements for molecular sizing, mixture analysis, polymers, supramolecular assemblies, or electrolytes. The DiffBBI is an inverse-probe design providing high 1H sensitivity for diffusion, while direct observation of low-gamma nuclei diffusion will require concentrated samples.
Access & Requirements: Requires dedicated hardware reconfiguration and staff scheduling. Individual training is reserved for sustained projects once feasibility is established; infrequent or one-off samples are handled by staff in service mode. (Note: Neo400Diff is managed separately by the Madsen research group).
Next steps: For technical specifications, sample preparation guidelines, and training prerequisites, please consult the Operations tab.
⚠️ Inquiry Required Prior to Scheduling
Solid-state NMR requires strict sample criteria, literature vetting, and staff setup. Before requesting time or training, please consult the Solid-State NMR Inquiries section located under the Operations menu for sample requirements, instrument limits, and submission details.
Best choice: Neo400Jack (4 mm MAS)
Application: Magic-angle spinning experiments on dry powders, crystalline materials, and solid polymers (e.g., 13C, 29Si, 31P CP/MAS).
Access & Requirements: Rotor packing, setup, and data collection are initially handled by staff in service mode due to hardware constraints and equipment risk. Independent access requires dedicated hands-on training and a demonstrated, sustained project need.
Next steps: For sample requirements, hardware limits, and inquiry procedures, please consult the Operations tab.
Two acquisition parameters primarily control 2D experiment quality and time: Number of Scans (NS) and Number of Increments (NI).
NS (scans per increment) sets the signal averaging at each point in the indirect dimension. Because most 2D sequences (HSQC, HMBC, COSY) use sensitivity-enhanced detection and efficient phase cycling, useful spectra often need far fewer scans than a comparable 1D experiment. The right NS depends primarily on your sample's concentration:
- 1–2 scans: Well-concentrated samples (routine 10–80 mM small molecules) — signal is already strong.
- 4–8 scans: Moderately dilute samples where a bit of extra averaging improves clarity.
- 16–32 scans: Dilute or limited-quantity samples needing meaningfully more signal averaging.
- 64, 96, or even 128 scans: Extremely dilute samples, most common in natural products characterization where material is scarce and concentration is low.
Increasing NS raises signal-to-noise only with the square root of scans, so doubling NS gives just a ~40% SNR gain — a costly trade for marginal improvement. At the high end of this range, combined with high increment counts (NI), a single 2D experiment can take well over a full day, so these settings should be used deliberately and coordinated with staff rather than as a default.
NI (increments in the indirect dimension) sets the resolution along the F1 axis. Total experiment time scales with NS × NI, so doubling NI roughly doubles run time for a fixed NS. The right NI depends on how much you need to resolve overlapping signals in the indirect dimension:
- 128 or 256: Coarse resolution for quick structural checks or routine assignments — sufficient when peaks are reasonably well separated.
- 400 or 512: Higher resolution for crowded or overlapping spectra where signals need to be cleanly separated in F1.
A coarser NI is often perfectly adequate for routine work, since it's the total experiment time — not the appearance of resolution — that scales directly with this choice. Combined with high NS on a dilute sample, a high-NI 2D experiment (HMBC especially) can easily run well over a full day, so increasing NI should be a deliberate decision based on demonstrated need (visibly overlapping cross-peaks at lower NI), not a default starting point.
COSY — Shows ³J ¹H-¹H scalar couplings (2–3 bonds). Used to identify spin systems and proton connectivity. Typical time: 10–30 min.
TOCSY — Shows extended ¹H-¹H relayed couplings through spin systems. Used to map entire spin systems (e.g., sugar residues). Typical time: 30–60 min.
HSQC — Shows ¹J ¹H-¹³C direct bonds (CH, CH₂, CH₃). Used to assign protonated carbons; the first heteronuclear 2D experiment run. Typical time: 20–60 min.
HMBC — Shows ²J–⁴J ¹H-¹³C long-range couplings. Used to connect to quaternary carbons and resolve branching. Typical time: 1–4 hrs.
H2BC — Shows ²J ¹H-¹³C geminal couplings only. Used for clean methylene (CH₂) assignments and to confirm HMBC data. Typical time: 1–3 hrs.
NOESY — Shows through-space ¹H-¹H dipolar interactions (<5 Å). Used to determine stereochemistry and 3D conformation (MW >800 Da). Typical time: 1–3 hrs.
ROESY — Shows rotating-frame NOE (positive for all molecular weights). Used for mid-sized molecules (500–1500 Da) where NOESY fails. Typical time: 1–3 hrs.
Internal PO Submission Process
How to fill out an Analytical Services ISR
Supplier: "VT Chemistry NMR Lab"
External Measurement Request
Contact Ken Sharp-Knott
kknott@vt.edu
540-231-0885
Walkup Instruments (No Reservation Needed)
- Neo400HT: 20 minute hard limit per sample
- JEOL ECZL400: 60 minute daytime limit per sample
- Neo400Jack: Prioritized for scheduled use of specialty probes
- Neo500BBO & Neo600TCI: No formal limit, but experiments exceeding 2 hours should be moved to the night queue when possible
Reservation Only Instrument
- Neo500Oxford: Direct link to FACES Scheduling System
- FACES Group: VATECHNMR
- Can reserve up to the minute — No shows risk loss of privileges
In all cases, when possible run non-urgent experiments longer than 2 hours during the overnight queue to maintain fair access for all users.
All data automatically uploaded to LOGS server:
URL: https://nmrsc.chem.vt.edu/asds
Login: Use your group's shared facility login (not your personal VT PID)
- Download datasets from LOGS to your local computer
- Process in MNova (facility standard software)
- Save MNova file (each file should contain experiments for ONE compound)
- Site license provided by facility upon completion of training
- Must connect to VT network for validation
- On-campus: eduroam
- Off-campus: Cisco Secure Client VPN
User Data Storage Recommendations: Download and archive your data promptly and systematically.
- Back up both the raw LOGS zip and the processed .mnova file for every sample, stored together in one folder.
- Never leave data in a Downloads folder — move it to permanent group storage the same day.
The NMR Facility provides solid-state NMR capabilities on our Neo400Jack spectrometer (400 MHz), configured with a specialized 4 mm Magic-Angle Spinning (MAS) probe.
Solid-state NMR is a powerful technique for characterizing insoluble materials, crystalline polymorphs, crosslinked polymers, and inorganic frameworks. Because SSNMR involves complex probe setups, high-power RF pulses, and rotor packing risks, access is carefully managed through a feasibility-first workflow.
Spinning Speeds: 15 kHz max; routine runs typically capped at 10–12 kHz.
Supported Experiments: Routine operations focus on standard direct detection (Bloch decay) and cross-polarization (CP/MAS) for heteronuclei, including 13C, 29Si, 31P, and 27Al.
Abundant Nuclei Limitations: A 15 kHz spinning rate is insufficient to average out strong homonuclear dipolar couplings for abundant spin-1/2 nuclei such as 1H and 19F. Without ultrafast MAS (>60 kHz) or specialized homonuclear decoupling sequences, spectra for these nuclei remain broad and poorly resolved.
Biomacromolecules: This instrument is not configured for biomolecular SSNMR (such as 1H-detected HCN experiments on proteins). Intact proteins and complex biomacromolecules requiring high-resolution proton detection are not viable on this system.
Proper rotor packing is critical for probe safety and spinning stability.
Physical Form: Samples must be homogeneous, finely ground, free-flowing dry powders. Coarse granules, sticky materials, waxes, or rubbers cannot be packed evenly and will cause unstable spinning or rotor crashes.
Sample Mass: A 4 mm zirconia rotor typically requires 50 to 100 mg of material, depending on bulk packing density.
Safety and Chemical Stability: Samples must be non-conductive, chemically stable, non-explosive, and non-corrosive. Conductive materials (such as carbon black or metals) can cause electrical arcing and destroy the probe. If your material is air- or moisture-sensitive, packing must be coordinated with staff to use a glovebox.
SSNMR requires significant facility support, specialized hardware tuning, and close oversight. To protect instrument hardware and ensure research productivity, we use the following process:
Feasibility Assessment: Before any instrument time or training is scheduled, researchers must consult with facility staff. We evaluate project goals, sample properties, and one to two peer-reviewed literature papers detailing SSNMR parameters on comparable materials to determine if the experiment is viable on our hardware.
Service Mode / Initial Runs: All one-off measurements and initial feasibility trials are conducted exclusively by facility staff in service mode.
User Training: Hands-on training toward independent instrument access is reserved for sustained, ongoing research projects once experimental viability has been demonstrated.
To initiate a project, please contact facility staff with an overview of your research goals, sample composition, target nuclei, and relevant literature examples.
The facility offers dedicated pulsed-field-gradient (PFG) diffusion measurements using a DiffBBI probe coupled with a high-power 60 A gradient amplifier.
Diffusion-ordered spectroscopy (DOSY) allows researchers to measure molecular self-diffusion coefficients, estimate hydrodynamic radii, monitor supramolecular assembly or aggregation, and visually separate components in chemical mixtures based on size and mobility.
Gradient Performance: Standard solution NMR probes generate modest gradient strengths (~50 G/cm). Our dedicated 60 A diffusion system delivers extremely strong pulsed field gradients (up to ~1700 G/cm), enabling the measurement of very slow-diffusing species, high-molecular-weight polymers, supramolecular aggregates, and viscous samples.
1H and 19F Sensitivity: The DiffBBI is an inverse-detection probe with the inner coil tuned to 1H (and 19F), delivering maximum sensitivity for proton-detected diffusion measurements.
Broadband Nuclei: Heteronuclei (such as 7Li, 23Na, and 31P) can be observed directly via the outer broadband coil. Because sensitivity for outer coils is considerably lower, direct X-nucleus diffusion experiments require concentrated samples (typically tens to hundreds of mM, or neat/electrolyte solutions) to yield sufficient signal.
Diffusion measurements are exceptionally sensitive to sample convection and viscosity:
Tubes and Volume: Standard 5 mm NMR tubes are used. Maintain a consistent sample volume (500 to 600 uL) to ensure the liquid column is properly centered within the coil and to minimize thermal convection.
Sample Quality: Solutions must be fully dissolved and free of suspended particles, precipitates, or dust, which distort diffusion decays.
Temperature and Solvents: Accurate diffusion values require precise temperature equilibrium. If your experiments involve low-viscosity organic solvents or non-ambient temperatures, specialized convection-compensated pulse sequences may be required.
Setting up the diffusion system involves a dedicated probe change, cabling reconfiguration, and specialized gradient calibration. Individual training requires substantial staff time and is managed as follows:
Initial Inquiry and Literature Review: Contact staff with your target species, expected diffusion coefficients, solvents, and one or two literature references demonstrating PFG/DOSY measurements on similar systems.
One-Off / Infrequent Samples: Projects requiring only occasional measurements or single sample screens are run by facility staff in service mode.
Independent User Training: Dedicated hands-on training is provided for sustained, ongoing research projects once feasibility on our system is confirmed—either through clear literature precedents or an initial staff-assisted trial. Trained users are granted permissions to reserve time and run routine diffusion experiments independently.
To discuss diffusion measurements or evaluate experimental setup, please contact facility staff with your project details and references.
Technical reference materials for planning experiments, selecting parameters, and understanding NMR fundamentals.
Sample Preparation Essentials
| REQUIREMENT | SPECIFICATION |
|---|---|
| Tube | Straight, undamaged 5mm tube (high-quality for qNMR and VT) |
| Volume | ~0.6 mL (40-50mm liquid height in tube) |
| Solution | Fully dissolved, clear, no particulates or bubbles |
| Solvent | Deuterated (CDCl₃, DMSO-d₆, D₂O, CD₃OD, CD₃CN, acetone-d₆, toluene-d₈, benzene-d₆) |
| Cleanliness | Wipe tube exterior with lint-free tissue before insertion |
- FORMAT: GROUPID-USERINITIALS-SHORTSAMPLEID
- EXAMPLE: WS2-KK-SK21
- RULES: Alphanumeric characters only - no spaces, periods, or special characters
- REQUIRED: Write GROUP ID prominently around cap (required for sample identification)
- Use BLACK SHARPIE (fine-tipped) on light colored cap
- Include sample ID or your initials (strongly recommended to distinguish your samples from groupmates)
- Dark or illegible caps not allowed — slows troubleshooting and makes orphaned samples harder to track
- No tape, parafilm, or labels attached to tubes — write directly on cap only
- Damaged or poor-quality tubes: Chips, bends, or scratches degrade shimming and cause spinning issues or distorted peaks. Retire questionable tubes, especially for VT or quantitative work.
- Incorrect sample volume or height: A liquid column far from 40–50 mm underfills or overfills the coil, hurting sensitivity and resolution. Target ~0.6 mL.
- Incomplete dissolution, particulates, or bubbles: Undissolved material or bubbles cause broad, unstable lines. Filter or let settle before running.
- Incorrect sample depth in spinner: Always set depth with the gauge — wrong depth causes weak signal and hard-to-shim spectra.
- Poor shimming: Shows up as broad or asymmetric peaks— more scans won't fix it. Before blaming shimming, first rule out the four causes above.
Quick Reference Guides
Cost consideration: Deuterated solvents vary significantly in price. CDCl₃ and DMSO-d₆ are relatively inexpensive, while D₂O, CD₃OD, and specialty solvents (DMF-d₇, pyridine-d₅) are more costly. Plan accordingly for budget-sensitive projects.
DMSO-d6 (Dimethyl sulfoxide-d6)
- Residual 1H peak: 2.50 ppm (quintet)
- Residual 13C peak: 39.52 ppm (septet)
- Boiling point: 189 °C
- Freezing point: 19 °C
- Notes: Polar aprotic solvent. Freezes easily near room temperature (19 °C). Hygroscopic, so moisture often appears as a broad H2O peak around 3.33 ppm. Exchanges slowly with some labile protons, making OH and NH signals visible.
D2O (Deuterium oxide)
- Residual 1H peak: 4.79 ppm (at 25 °C; shifts ~ -0.01 ppm/°C with temperature and varies with pH/salt concentration)
- Residual 13C peak: None (requires an internal or external standard such as DSS or TSP at 0.00 ppm)
- Boiling point: 101 °C
- Freezing point: 4 °C
- Notes: For aqueous samples, salts, and biomolecules. Rapidly exchanges with labile OH, NH, and SH protons, causing those signals to disappear. Because the residual HOD peak moves with temperature and ionic strength, use DSS or TSP (0.00 ppm) for high-precision calibration.
CD3OD (Methanol-d4)
- Residual 1H peaks: 3.31 ppm (quintet, CHD2), ~4.87 ppm (singlet, OD/OH exchange peak; temperature- and water-dependent)
- Residual 13C peak: 49.00 ppm (septet)
- Boiling point: 65 °C
- Freezing point: -98 °C
- Notes: Protic solvent. Causes rapid exchange of labile protons (OH, NH, SH). Can slowly deuterate acidic C-H positions alpha to carbonyls and can cause solvolysis/methanolysis of reactive species such as acyl chlorides or esters.
CD3CN (Acetonitrile-d3)
- Residual 1H peak: 1.94 ppm (quintet)
- Residual 13C peaks: 1.32 ppm (septet, CD3), 118.26 ppm (singlet, CN)
- Boiling point: 82 °C
- Freezing point: -45 °C
- Notes: Aprotic solvent with low viscosity yielding sharp resonance lines. Residual dissolved water typically appears nearby at ~2.13 ppm, so inspect both peaks carefully before integrating or interpreting that region.
Acetone-d6
- Residual 1H peak: 2.05 ppm (quintet)
- Residual 13C peaks: 29.84 ppm (septet, CD3), 206.26 ppm (singlet, C=O)
- Boiling point: 56 °C
- Freezing point: -95 °C
- Notes: Volatile solvent allowing easy sample recovery. Moderately hygroscopic; residual water typically appears around 2.84 ppm. Can react with primary or secondary amines (forming imines/enamines), so avoid with amine-containing samples.
CDCl3 (Chloroform-d)
- Residual 1H peak: 7.26 ppm (singlet)
- Residual 13C peak: 77.16 ppm (triplet)
- Boiling point: 61 °C
- Freezing point: -64 °C
- Notes: Most common solvent for nonpolar to moderately polar organic compounds. Decomposes slowly over time and light exposure to generate trace DCl/HCl and phosgene; store over silver foil/molecular sieves or pass through basic alumina for acid-sensitive compounds. Residual water typically appears at ~1.56 ppm.
Toluene-d8
- Residual 1H peaks: 2.09 ppm (quintet, CD2H), 6.98 ppm (triplet, meta), 7.00 ppm (singlet/multiplet, para), 7.09 ppm (multiplet, ortho)
- Residual 13C peaks: 20.43 ppm (septet, CD3), 125.13 ppm (ortho), 127.96 ppm (para), 128.87 ppm (meta), 137.48 ppm (singlet, ipso)
- Boiling point: 111 °C
- Freezing point: -95 °C
- Notes: Wide liquid temperature range makes it ideal for high- and low-temperature VT studies. Strong aromatic diamagnetic ring-current effects can shift solute peaks compared to CDCl3. Complex aromatic multiplet region (6.95–7.20 ppm) can obscure analyte aryl protons.
Benzene-d6
- Residual 1H peak: 7.16 ppm (singlet)
- Residual 13C peak: 128.06 ppm (triplet)
- Boiling point: 80 °C
- Freezing point: 6 °C
- Notes: Common solvent for organometallic complexes, coordination chemistry, and polymers. Freezes easily near room temperature (6 °C), requiring care during VT low-temperature work. Strong anisotropic shielding shifts solute resonances significantly. Highly toxic and a known human carcinogen; handle exclusively in certified chemical fume hoods.
NMR Tubes & Consumables
- Quantitative NMR (qNMR): Use high-quality, precision tubes (e.g., Wilmad 528-PP)
- Variable Temperature (VT): VT-rated tubes (Class A) required for temperature extremes
- Cryoprobe work: Clean, undamaged tubes to protect expensive cryoprobes
| Tube Type | When to Use | Notes |
|---|---|---|
| Shigemi tubes | Limited sample volume (<300 μL) | Glass susceptibility-matched plugs; consult staff before use |
| Coaxial inserts | Lock solvent separate from sample | For samples incompatible with deuterated solvents |
| 3 mm tubes | Very limited sample quantity | Can be used in standard 5 mm probes with specialized spinner adapters/sleeves; consult staff for setup |
When co-authorship is expected:
- Substantial intellectual contributions to experimental design, data interpretation, or manuscript preparation
- Specialized technique development or troubleshooting beyond routine support
- Custom method development, extensive troubleshooting, or data analysis assistance
When acknowledgment (not co-authorship) is sufficient:
- Routine training and instrument access
- Standard walkup experiments without significant staff involvement
- Minor troubleshooting or parameter adjustments
Best practice: Discuss authorship expectations early in your project with facility staff to avoid misunderstandings.
When describing your NMR experiments in the Methods or Experimental section of manuscripts, cite relevant instrument details from the Instruments page. Include:
- Instrument name (e.g., "Bruker Avance Neo 600 MHz")
- Probe type (e.g., "Prodigy TCI cryoprobe")
- Field strength and observe frequency
Example Citation:
"¹H and ¹³C NMR spectra were acquired on a Bruker Avance Neo 600 MHz spectrometer equipped with a Prodigy TCI cryoprobe. NMR data reported in this work were obtained at the Virginia Tech Chemistry NMR Facility (RRID:SCR_027587)."
- Specify solvent, temperature (if non-ambient), and spectrometer frequency
- Include coupling constants (J) in Hz for multiplets
- For quantitative NMR, describe relaxation delays, pulse angles, and any relaxation agents used
Laboratory Hours
Staffed Hours: 9a - 5p, M-F
24/7 access for trained users
Contact NMR Staff
Ken Sharp-Knott
NMR Facility Manager
kknott@vt.edu
540-231-0885
540-267-6502 (Emergencies Only)
Murthy Shanaiah, Ph.D.
NMR Spectroscopist
nmrns@vt.edu
540-231-8256
Emergency Contact
VT Environmental Health & Safety
540-231-5364
www.ehs.vt.edu
Kenny Smith
Facilities Manager
kesmith7@vt.edu
Drew Murphy
Safety Coordinator
drewmurphy23@vt.edu
Lab Address
Hahn Hall South 002
Virginia Tech
800 W. Campus Blvd.
Blacksburg, VA 24061