Bruker NMR User manual

NMR Thermometer
Variable Temperature Control Using the 2H Lock
System of AVANCE III HD Spectrometers
User Manual
Version 002
Innovation with Integrity
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NMR

Copyright © by Bruker Corporation
All rights reserved. No part of this publication may be reproduced, stored in a retrieval
system, or transmitted, in any form, or by any means without the prior consent of the
publisher. Product names used are trademarks or registered trademarks of their
respective holders.
This manual was written by
Application & Electronics Departments
© July 11, 2014 Bruker Corporation
P/N: Z33085
DWG: Z4D12031
For further technical assistance for this product, please do not hesitate to contact your
nearest BRUKER dealer or contact us directly at:
Bruker Corporation
Industriestrasse 26
8117 Fällanden
Switzerland
Phone: + 41 44 825 91 11
FAX:+ 41 44 825 9696
E-mail: [email protected]
Internet: www.bruker.com

Contents
Z33085_2_002 3
Contents
1Introduction......................................................................................................................................... 5
2Principle of NMR Thermometer......................................................................................................... 7
3Requirements...................................................................................................................................... 9
4Getting Started.................................................................................................................................. 11
4.1 The edlock Menu............................................................................................................... 11
4.2 Setting up the NMR System for the NMR Thermometer ................................................... 13
4.3 Examples........................................................................................................................... 15
4.3.1 Monitoring Mode................................................................................................................ 16
4.3.2 Regulation Mode ............................................................................................................... 17
5Advanced Operation ........................................................................................................................ 19
5.1 Define a New Solvent........................................................................................................ 19
5.2 Selection of NMR Thermometer Compounds ................................................................... 21
5.2.1 Predefined Solvents for the NMR Thermometer ............................................................... 22
5.2.2 Technical Considerations .................................................................................................. 23
5.2.3 Considerations for Shimming with Topshim ...................................................................... 24
6Applications ...................................................................................................................................... 27
6.1 Identical Chemical Shifts at Different Spectrometers ........................................................ 27
6.2 Identical Chemical Shifts for Experiments with Different Heating due to Experimental
Conditions (Temperature Compensation) ......................................................................... 28
6.2.1 RF Heating ........................................................................................................................ 28
6.2.2 Heating caused by Spinning Speed (HR-MAS)................................................................. 29
7Frequently Asked Questions (FAQ)................................................................................................ 31
8Contact .............................................................................................................................................. 33
List of Figures................................................................................................................................... 35
Index .................................................................................................................................................. 37

Contents
4Z33085_2_002

Introduction
Z33085_2_002 5
Introduction
This manual is planned as a user manual with limited technical detail. The main focus is on
usability, whereas a few easy examples are provided showing how to get started with this
new tool. Through use of this manual the user should get an idea for what the NMR
Thermometer™ might be used for.
The comparability of data (chemical shifts) and results derived from NMR data (diffusion data,
relaxation measurements), as well as the quality of the NMR spectra, depend on an accurate
and precise temperature measurement. That is the reason why the temperature
measurement should ideally take place inside the NMR tube and not outside of it. In general
the temperature sensor of the probe is not reflecting the real situation inside the NMR tube.
The NMR Thermometer not only monitors the temperature, but also compensates for
different heating effects (e.g. RF heating) that occur during an NMR experiment.
1

Introduction
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Principle of NMR Thermometer
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Principle of NMR Thermometer
The NMR Thermometer measures the temperature inside the sample by observing the
chemical shifts of two 2H signals using the lock channel (LTRX board) of the NMR system.
The distance between the two signals is transferred into a temperature and directly used by
the temperature control unit (BVT) for regulation. Thus, the NMR Thermometer acts as a
temperature sensor (see figure below).
To obtain the second lock signal, a thermometer substance needs to be added. One of the
signals should also be temperature dependent.
Figure 2.1: Principle of the NMR Thermometer.
2

Principle of NMR Thermometer
8Z33085_2_002

Requirements
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Requirements
Hardware: Avance III HD. A hardware upgrade is required for Avance III, whereas an update
to SmartVT™ and Digilock 2G is required.
Software: TopSpin version 3.2 or higher.
Firmware: Versions for Avance III HD.
3

Requirements
10 Z33085_2_002

Getting Started
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Getting Started
This chapter provides a short and straightforward introduction on how the NMR Thermometer
works and guides you through the first steps using the NMR Thermometer. As an overview,
the steps include:
• Preparation of the edlock table if not yet done.
• Locking on the corresponding solvent used for the NMR Thermometer.
• Optimizing the shim and lock phase.
• Activating the NMR Thermometer in the variable temperature control.
• Performing self-tuning of the variable temperature unit. This will optimize the regulation
parameters for both the VT control with the sensor and the NMR Thermometer.
• Calibration of the spectrometer for measurements of real samples after the setup of the
NMR Thermometer is finished.
The edlock Menu
First we will provide a short introduction to the software implementation (edlock, edte).
Start edlock by typing edlock on the TopSpin command line. The edlock window opens up.
The new edlock (starting for TopSpin 3.0 and higher) contains both the solvent list (formerly
edsolv in the Edit Solvent Parameters figure below) and the lock parameters for every solvent
(see the The Submenu Lock figure below).
Figure 4.1: The Submenu Bar: Solvent.
The Edit Solvent Parameters window allows you to enter several parameters for the solvent,
the melting point setting, and the boiling point of the solvent:
4
4.1

Getting Started
12 Z33085_2_002
Figure 4.2: Edit Solvent Parameters.
In the submenu Lock window the solvents are listed, along with the probe for which the
definition is valid (generic or specific probe), as well as other lock parameters (lock power,
lock regulation triplet etc.).
Figure 4.3: The Submenu Lock.
By executing a right mouse click on a solvent entry, a pull-down menu opens with the option
for editing the lock parameters:

Getting Started
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Figure 4.4: Edit Lock Parameters.
Every solvent entry contains information about every 2H signal for that compound.
It is possible to define all the signals for solvents with more than one 2H signal either as
Signal, as Lock (signal used for field lock) or as Temperature (signal used for the NMR
Thermometer).
For any NMR Thermometer substance, temperature and shift values can be added or
imported (see below). The NMR Thermometer has its own lock power (figure above). For
methanol (NMR Thermometer, standard sample: 99.8% deuterated methanol) a default
solvent with corresponding lock parameters and temperature-shift value has already been
defined.
Setting up the NMR System for the NMR Thermometer
Since the NMR Thermometer is observing a 2H signal, the system has to be properly set up
(lock, shimming, optimal lock parameters for the field lock and NMR Thermometer), similar to
any other NMR measurement. This means that you should perform an automatic tuning and
matching (atma), lock-in, and shimming. The lock-in procedure works as usual (type lock on
the command line and select the solvent). If you lock directly on a solvent dedicated for the
NMR Thermometer (methanol or another solvent), a temperature value is immediately
shown, either in the monitoring mode or regulation mode (figure below). After that you can
perform topshim. A decent line shape (no unusual line splitting) is mandatory for an exact
temperature measurement inside the sample.
4.2

Getting Started
14 Z33085_2_002
Figure 4.5: Edte Window: NMR Thermometer monitoring mode (disabled, top), regulation mode
(enabled, middle) and the selection of both modes in the Configuration menu of the edte window
(bottom).
Another important parameter is the lockphase, which can be optimized automatically by
starting autophase (BSMS display). The procedure used for autophase is selected in the
edlock window (Lock Level Default, Spectrum, and Enhanced Lock Level in the figure below).
Figure 4.6: Selection of the Auto Phase Algorithm.
To prevent saturation, the Lockpower and lockgain for both lock channels should be
optimized as well.
Since the NMR Thermometer contains both the lock and the temperature regulation
components, the PID values for the temperature regulation need to be adjusted for each by
using selftune. You will be notified by the system if a selftune is recommended:
Figure 4.7: Selftune warning about PID parameters misfit.

Getting Started
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Figure 4.8: Starting the selftune procedure from the edte window.
The selftune should be carried out on both temperature channels (All).
Examples
An easy example to begin with is to use the methanol sample (standard sample: 99.8%
deuterated).
Since this sample is the reference for the NMR Thermometer, the solvent entry in edlock
containing the temperature and shift values is already predefined.
As mentioned, the NMR Thermometer is running in two different modes: monitoring and
regulation mode (see above).
Assume that the lock parameters are already optimized.
4.3

Getting Started
16 Z33085_2_002
Monitoring Mode
The following steps need to be performed:
• Insert sample.
• Tune and match by using the atma command.
• Lock-in – temperature appears.
• Topshim.
• Selftune.
Figure 4.9: Selftune in Progess.
• Edte – disable NMR Thermometer (if not already done).
• Change target temperature (edte for instance, a 10K temperature jump).
As an exercise we will perform a temperature jump (e.g. 10K) and follow the different
temperature and other BSMS values (flow/heater) in the monitoring window (edte -
Monitoring, as well as, activate NMR Sensor Temperature, NMR Thermometer, Target
Temperature, Current Power etc.).
4.3.1

Getting Started
Z33085_2_002 17
Figure 4.10: Monitoring several BSMS values during a temperature jump.
Regulation Mode
The following steps need to be performed:
• Insert sample.
• Tune and match – atma.
• Lock-in – temperature value appears.
• Topshim.
• Selftune (maybe already done in example 1).
• Edte – enable NMR Thermometer.
• Perform an experiment with internal RF heating (e.g. TOCSY).
After setting up the system (lock, shim) and enabling the NMR Thermometer (edte) the
sample temperature is used for temperature regulation, which is visible on the status bar:
Figure 4.11: TopSpin status bar with NMR Thermometer enabled.
To test the performance of the NMR Thermometer start a TOCSY experiment and follow the
temperature values (sensor, NMR Thermometer) in the monitoring window of the VTU display
(edte). One can nicely see that the temperature inside the sample increases over a certain
4.3.2

Getting Started
18 Z33085_2_002
period of time and that the system immediately reacts to that by reducing the heater power
(figure below - lower part), and hence the sensor temperature (figure below - upper part,
white line).
Figure 4.12: Monitoring of the sensor and the sample temperature in edte during a TOCSY experiment
In the figure above, the upper part shows the temperature of the sensor and the NMR
Thermometers; the lower part shows the heater power.

Advanced Operation
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Advanced Operation
Define a New Solvent
To work with your own NMR Thermometer substances, you first have to define a new solvent
in the edlock table.
Select a solvent which is similar to your mixture (similar lock parameters) and click the right
mouse button. In the resulting pull-down menu you can add the new solvent:
Figure 5.1: Adding New Solvents.
In the edit lock parameters window the signals can be defined (Shift) and assigned (Type) as
Lock, Signal or Temperature:
5
5.1

Advanced Operation
20 Z33085_2_002
Figure 5.2: Assign Signals to Type of Signal (Signal, Lock, Temperature).
In the next step you should import the shift-temperature values (.csv or .xml format) or fill in
the values manually. You can also create your own .xml (see below).
Figure 5.3: Dialog for importing temperature shift value files.
The .xml file (figure below) contains the name of the solvent (identical with the solvent name)
and two shift values, one for the field shift and one for the temperature shift. The values have
to be identical with the values defined for the particular solvent in edlock.
Figure 5.4: Example of a shift-temperature file in .xml format.
After the import the shift and temperature value are filled in the edlock table for the selected
solvent and used afterwards for the lock-in process Create a new XML file: