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JEOL JNM-ECA Series User Manual

Solid measurement
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INMECAXS_V50-SLD-2
FEB2010-08110273
Printed in Japan
INSTRUCTIONS
JNM-ECA Series
JNM-ECX Series
(Delta V5.0)
SOLID
MEASUREMENT
USER'S MANUAL

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Summary of Contents for JEOL JNM-ECA Series

  • Page 1 INSTRUCTIONS JNM-ECA Series JNM-ECX Series (Delta V5.0) SOLID MEASUREMENT USER’S MANUAL For the proper use of the instrument, be sure to read this instruction manual. Even after you read it, please keep the manual on hand so that you can consult it whenever necessary.
  • Page 2 JNM-ECA Series JNM-ECX Series (Delta V5.0) SOLID MEASUREMENT USER’S MANUAL JNM-ECA Series JNM-ECX Series In the ECA or ECX NMR instrument, solid-state NMR measurement becomes possible when you add optional attachment, such as solid probe, to the standard composition. This manual explains about cautions, measurement conditions, processing...
  • Page 3 JEOL service office; and adjusting the specified parts that only field service technicians employed or authorized by JEOL are allowed to adjust, such as bolts or regulators which need to be tightened with appropriate torque. Doing any of the above might result in instrument failure and/or a serious accident. If any such modification, attachment, replacement or adjustment is made, all the stipulated warranties and preventative maintenances and/or services contracted by JEOL or its affiliated company or authorized representative will be void.
  • Page 4 Article 7. (Exemption from Liability) JEOL shall not be liable for any damages or losses incurred by you or any third party or for any claim of a third party against you arising out of or in relation to the use of the Licensed Software.
  • Page 5 If the product is used for business purposes and you want to discard it, please contact your JEOL dealer, who will advise you about the end-of-life disposal arrangements. ■ Outside the European Union...
  • Page 6 NOTATIONAL CONVENTIONS AND GLOSSARY ■ Examples for general notations Important precautions for use, which, if not followed, may result in — CAUTION — : damage to or problems with the device itself. Additional points to remember regarding the operation. A reference to another section, chapter or manual. Numbers indicate a series of operations that achieve a task.

  • Page 7: Table Of Contents

    CONTENTS SAFETY PRECAUTIONS PRECAUTIONS FOR USE 1. OUTLINE OF SOLID-STATE NMR MEASUREMENT SOLID-STATE NMR SYSTEM ............1-1 DIFFERENCE BETWEEN SOLID-STATE NMR AND SOLUTION NMR .................. 1-2 2. FUNDAMENTALS OF SOLID-STATE NMR MEASUREMENT INTERACTIONS INFLUENCING SOLID-STATE NMR SPECTRUM................... 2-1 MAGIC ANGLE SPINNING..............2-2 HIGH POWER DECOUPLING.............
  • Page 8 CONTENTS 4. ADJUSTMENT OF MEASUREMENT CONDITIONS AND PROCESSING CONDITIONS SETTING PULSE WIDTH IN SINGLE PULSE MEASUREMENT ..................4-1 SETTING WAITING TIME IN SINGLE PULSE MEASUREMENT ..................4-2 SETTING CONTACT TIME IN CP METHOD ........4-3 SETTING WAITING TIME IN CP METHOD ........4-4 SETTING SAMPLING POINT (X_POINTS) ........4-5 HOW TO USE FORWARD LINEAR PREDICTION ......4-6 HOW TO USE BACKWARD LINEAR PREDICTION......4-7 5.

  • Page 9: Safety Precautions

    • Be sure to read the “Safety Precautions” section of the manuals for the accessories attached to or built into the instrument. • If anything is unclear, please contact your JEOL service office. NMECAXS_V50-SLD-2...
  • Page 10 WARNING for Installation • Do not attempt to install the instruments by yourself. Installation work requires professional expertise and JEOL is responsible for the in- stallation of the instruments and related attachments purchased from JEOL. Consult your JEOL service office.

  • Page 11: Precautions For Use

    PRECAUTIONS FOR USE Important precautions, which, if not followed, may result in damage to the device itself, are described below. • The probe may become damaged if the data-acquisition time is too long. • Liquid samples, samples whose volume changes (such as between the solid and liquid states) when due to a change in temperature, and sublimating materials cannot be measured.

  • Page 12: Outline Of Solid-State Nmr Measurement

    OUTLINE OF SOLID-STATE NMR MEASUREMENT SOLID-STATE NMR SYSTEM ................ 1-1 DIFFERENCE BETWEEN SOLID-STATE NMR AND SOLUTION NMR ........................1-2 NMECAXS_V50-SLD-2...

  • Page 13: Solid-State Nmr System

    1 OUTLINE OF SOLID-STATE NMR MEASUREMENT SOLID-STATE NMR SYSTEM High-Resolution solid-state NMR measurement by techniques such as cross-polarization magic-angle spinning (CPMAS) method becomes possible when you add optional at- tachments (such as a probe for the solid-state measurement) to the standard composition of JNM-ECA/ECX series.

  • Page 14: Difference Between Solid-State Nmr And Solution Nmr

    1 OUTLINE OF SOLID-STATE NMR MEASUREMENT DIFFERENCE BETWEEN SOLID-STATE NMR AND SOLUTION NMR The feature of solid high-resolution NMR that makes it different from solution NMR is the ability to measure a solid sample as it is. In solution NMR, since an observed mole- cule is dissolved in a solvent, almost all magnetic interactions except the spin-spin inter- action can be eliminated by rapid molecular motion.

  • Page 15: Fundamentals Of Solid-State Nmr Measurement

    FUNDAMENTALS OF SOLID-STATE NMR MEASUREMENT INTERACTIONS INFLUENCING SOLID-STATE NMR SPECTRUM..2-1 MAGIC ANGLE SPINNING................2-2 HIGH POWER DECOUPLING................. 2-3 2.3.1 CW (Continuous Wave) Decoupling............2-3 2.3.2 TPPM (Two Pulse Phase Modulation) Decoupling ........2-3 SINGLE PULSE MEASUREMENT ..............2-4 CROSS POLARIZATION.................. 2-5 2.5.1 Principle of Cross Polarization..............

  • Page 16: Interactions Influencing Solid-State Nmr Spectrum

    2 FUNDAMENTALS OF SOLID-STATE NMR MEASUREMENT INTERACTIONS INFLUENCING SOLID-STATE NMR SPECTRUM Usually, the interactions in the NMR are expressed as the sum of the seven interactions shown below. H = H σ Zeeman interaction Chemical shift isotropy σ Spin-spin interaction (J coupling) isotropy Chemical shift anisotropy Spin-spin interaction anisotropy Magnetic dipole-dipole interaction...

  • Page 17: Magic Angle Spinning

    2 FUNDAMENTALS OF SOLID-STATE NMR MEASUREMENT MAGIC ANGLE SPINNING Magic Angle Spinning (MAS) is a spinning technique in which the sample rotates on an axis at 54.74 degree (= arccos ) with respect to the static magnetic field. MAS is the most fundamental and important technique in the solid-state NMR.

  • Page 18: High Power Decoupling

    2 FUNDAMENTALS OF SOLID-STATE NMR MEASUREMENT HIGH POWER DECOUPLING When H and C are directly coupled, the dipole interaction with H is about 20 kHz. In order to completely eliminate the dipole interaction with the H high-power decoup- ling of about 60-80 kHz is usually required. Since there is a strong dipole interaction be- tween the protons in an organic compound, you cannot use the technique of broad-band decoupling that is used in the solution NMR.

  • Page 19: Single Pulse Measurement

    2 FUNDAMENTALS OF SOLID-STATE NMR MEASUREMENT In addition, since TPPM decoupling also decreases the interference between MAS speed and CW decoupling, it also prevents the line-width from increasing under high-speed MAS. TPPM decoupling is especially effective in the following cases. •...

  • Page 20: Cross Polarization

    2 FUNDAMENTALS OF SOLID-STATE NMR MEASUREMENT CROSS POLARIZATION The Cross-Polarization (CP) method is the technique most generally used in solid-state NMR. The CP method is usually called the “CPMAS” method because it is used in com- bination with MAS. Usually, CPMAS measurement has the following advantage when comparing it with the single-pulse measurement.

  • Page 21: Notes Of Cross Polarization

    2 FUNDAMENTALS OF SOLID-STATE NMR MEASUREMENT 2.5.2 Notes of Cross Polarization Since signal intensity depends on the contact time in the CPMAS method, it is necessary to search for the optimum conditions ( Sect. 4.3). Moreover, the cross-polarization condition under high-speed MAS depends on the spin- ning speed.

  • Page 22: Setting Of Instrument Conditions

    SETTING OF INSTRUMENT CONDITIONS Chapter 3 explains the methods for setting the measurement conditions that are dependent on the instrument. Basic measurement conditions are preset to suitable values at delivery time. However, if a long time passes and the state of the instrument changes, the preset values may shift and the signal and noise ratio may decrease.

  • Page 23: Precaution For Operation

    3 SETTING OF INSTRUMENT CONDITIONS PRECAUTION FOR OPERATION Read these general precautions before operating the instrument. CAUTION • Liquid samples, samples whose volume changes (such as between the solid and liquid states) when due to a change in temperature, and sub- limating materials cannot be measured.
  • Page 24 3 SETTING OF INSTRUMENT CONDITIONS CAUTION • Carefully read the instruction manual then perform the magic angle spinning. There is a danger of destroying the probe. Heating the sample tube and its temperature calibration when in high-speed When the sample rotates at a high speed, the rate of temperature increase is approxi- mately the square of the spinning speed.

  • Page 25: Adjustment Of Magic Angle

    3 SETTING OF INSTRUMENT CONDITIONS For a sample that deteriorates, melts, ignites, or explodes when the temperature rises, decide the setting temperature by taking into consideration the temperature increase due to spinning. Tuning after variable temperature After the sample reaches the measurement temperature, be sure to tune the probe. When variable temperature (VT) ends If spinning is stopped or samples are exchanged immediately after VT measurement is terminated, it will cause a problem.

  • Page 26: Setting Of Irradiation Frequency

    3 SETTING OF INSTRUMENT CONDITIONS After magic-angle adjustment is completed, display the Queue tab and ter- minate the measurement. Adjustment of the magic angle may change the resolution. Be sure to check the resolution according to Sect. 3.5 “Adjustment of the resolution”, and adjust the shim values if necessary.

  • Page 27: Setting Pulse Width

    3 SETTING OF INSTRUMENT CONDITIONS SETTING PULSE WIDTH Set the pulse width for the solid-state NMR measurement the same as for the liquid NMR measurement. At first, measure the 360 ° pulse width, and set the 90° pulse width to 1/4 of the 360°...
  • Page 28 3 SETTING OF INSTRUMENT CONDITIONS Click the Sumit button. The pulse occurs, and the measurement starts. When the measurement is completed, the nD Processor window automatically opens. Perform data processing. Refer to the user’s manual “Data processing” for instruction on processing the data obtained by the array measurement.

  • Page 29: Adjustment Of Resolution

    3 SETTING OF INSTRUMENT CONDITIONS ADJUSTMENT OF RESOLUTION Set the adamantane standard sample. Perform spinning. Load the pulse sequence: setup/reso_adjust_adm.jxp in the Experiment Tool. Confirm that repeat was selected. Click the Submit button. The pulses occur, and the measurement starts. Adjust the phase by the following procedure.

  • Page 30: Reference Setting

    3 SETTING OF INSTRUMENT CONDITIONS REFERENCE SETTING In the solid-state NMR, the reference cannot be corrected by using the lock signal as in the solution NMR. Therefore, the reference is set up using the spectrum of an exter- nal-reference sample. There are two methods for setting the reference: setting in the Delta and setting using the Z0 shim.

  • Page 31: Reference Setting By Using Z0 Shim

    3 SETTING OF INSTRUMENT CONDITIONS Before repeating the above procedure, be sure to click the Undo button to cancel the settings. For the external reference, use the spectrum that was measured just before or was measured immediately after the measurement of the target spectrum. If a long time period exists between these two measurements, the error of the chemical shift be- comes larger due to the drift of the static magnetic field.

  • Page 32: Adjustment Of Cross-Polarization Conditions

    3 SETTING OF INSTRUMENT CONDITIONS ADJUSTMENT OF CROSS-POLARIZATION CONDI- TIONS Adjustment of CP（Cross-Polarization） conditions is performed to satisfy the Hart- mann-Hahn conditions. The Hartmann-Hahn conditions are different between low- speed spinning and high-speed spinning. Therefore, you need to adjust the conditions according to the spinning speed.

  • Page 33: Adjustment Of Cp Condition Under High Speed Spinning

    3 SETTING OF INSTRUMENT CONDITIONS 3.7.2 Adjustment of CP Condition under High Speed Spinning The Hartmann-Hahn conditions, taking into consideration spinning speed ω under high-speed spinning, are as follows: γ = γ + n・ ω （n = ± 1, ± 2） Under actual work conditions, set the value of irr_amp_cp and obs_amp_cp so that it satisfies the conditions for every spinning speed.

  • Page 34: Selecting A Method For Cross Polarization

    3 SETTING OF INSTRUMENT CONDITIONS Perform data processing. Refer to the user’s manual “Data processing” for processing the data obtained by the array measurement. After data processing, the result is displayed by selecting Linearize. Set up the obs_amp_grad value of Carbon13. In the spectra for which you carried out Linearize processing, the value of obs_amp_grad with the strongest signal intensity is the optimum value of cross-po- larization conditions.

  • Page 35: Adjustment Of Decoupling Conditions

    3 SETTING OF INSTRUMENT CONDITIONS ADJUSTMENT OF DECOUPLING CONDITIONS For a sample containing H, it is necessary to perform high-power decoupling ( Sect. 2.3). Since very strong RF pulses are used for high-power decoupling, it is necessary to decrease the decoupling power in the measurements in which the data acquisition time x_acq_time is 100 ms or more.

  • Page 36: Setting Of Xix Decoupling Conditions

    3 SETTING OF INSTRUMENT CONDITIONS 3.8.3 Setting of XiX Decoupling Conditions To perform XiX (X inverse-X) decoupling, adjust the pulse width: irr_width_xix. Set the standard sample glycine. Set irr_noise to XiX. Perform an array measurement for irr_ width_XiX The optimum value of irr_ width_XiX is around 1.85 or 2.85 times the recip- rocal of the spinning speed.

  • Page 37: Setting Of Cm Decoupling Conditions

    3 SETTING OF INSTRUMENT CONDITIONS 3.8.5 Setting of CM Decoupling Conditions To perform CM (Cosine Modulation) decoupling, adjust the pulse width of irr_width_cm and the phase-shift value of irr_phs_tppm. Set the standard sample glycine. Set irr_noise to CM. Perform an array measurement for irr_ width_cm and irr_ phs_tppm. Click the Submit button.

  • Page 38: Adjustment Of Measurement Conditions And Processing Conditions

    ADJUSTMENT OF MEASUREMENT CONDITIONS AND PROCESSING CONDITIONS Chapter 4 explains the method of adjusting measurement conditions and processing conditions. Although data can be obtained by using the initial values of the basic conditions for a measurement, more useful data can be obtained by using the optimum values for each sample.

  • Page 39: Setting Pulse Width In Single Pulse Measurement

    4 ADJUSTMENT OF MEASUREMENT CONDITIONS AND PROCESSING CONDITIONS SETTING PULSE WIDTH IN SINGLE PULSE MEASUREMENT Usually, the flip angle obs_angle_prep is set to 90 deg for a solid-state NMR measure- ment. However, for a sample with a very long relaxation time, making the flip angle small shortens the waiting time of relaxation_delay.

  • Page 40: Setting Waiting Time In Single Pulse Measurement

    4 ADJUSTMENT OF MEASUREMENT CONDITIONS AND PROCESSING CONDITIONS SETTING WAITING TIME IN SINGLE PULSE MEASUREMENT The optimum value of relaxation_delay in a single-pulse measurement is determinded by T of the observed nucleus. When the measurement is carried out using a 90° pulse, theoretically the accumulation efficiency (= signal intensity/accumulation time) becomes optimum if relaxation_delay is about 1.2 times the T of the observed nucleus (as shown...

  • Page 41: Setting Contact Time In Cp Method

    4 ADJUSTMENT OF MEASUREMENT CONDITIONS AND PROCESSING CONDITIONS SETTING CONTACT TIME IN CP METHOD The contact time (contact_time) is the time required to transfer the magnetization from H to C. The efficiency of the magnetization transfer changes depending on the length of the transfer time.

  • Page 42: Setting Waiting Time In Cp Method

    4 ADJUSTMENT OF MEASUREMENT CONDITIONS AND PROCESSING CONDITIONS SETTING WAITING TIME IN CP METHOD For the CPMAS method, the optimum value of relaxation_delay is determined by the T H. Theoretically, the accumulation efficiency (= signal-to-noise ratio/accumulation time) becomes optimum, if relaxation_delay is about 1.2 times the T value of H as shown in the following figure.
  • Page 43 4 ADJUSTMENT OF MEASUREMENT CONDITIONS AND PROCESSING CONDITIONS SETTING SAMPLING POINT (X_POINTS) The parameter x_points specifies the number of sampling points to acquire FID data. For a solid-state NMR measurement, this parameter is used to adjust the decoupling time. Since decoupling time is the same as acquisition time, it is expressed as x_acq_time. High-power RF will be input to the probe during x_acq_time.

  • Page 44: How To Use Forward Linear Prediction

    4 ADJUSTMENT OF MEASUREMENT CONDITIONS AND PROCESSING CONDITIONS HOW TO USE FORWARD LINEAR PREDICTION Forward linear prediction is a technique used for complementing the data by predicting the missing data from the acquired data when the entire data of FID is not acquired due to setting the sampling points too small.

  • Page 45: How To Use Backward Linear Prediction

    4 ADJUSTMENT OF MEASUREMENT CONDITIONS AND PROCESSING CONDITIONS HOW TO USE BACKWARD LINEAR PREDICTION Backward linear prediction is a technique used for predicting several points at the begin- ning of FID and replacing them. You can use it when the FID includes ringing. Moreover, backward linear prediction can predict several points at the beginning of FID that were missing in a measurement and extrapolate them.

  • Page 46: Multinuclear Measurement

    MULTINUCLEAR MEASUREMENT OUTLINE OF MULTINUCLEAR MEASUREMENT ........5-1 METHOD OF MEASURING RARE SPIN NUCLEUS OF SPIN 1/2 ....5-2 METHOD OF MEASURING F..............5-2 METHOD OF MEASURING NUCLEUS OF SPIN 1 ........5-3 METHOD OF MEASURING NUCLEUS OF HALF-INTEGER SPIN ... 5-3 NMECAXS_V50-SLD-2...

  • Page 47: Outline Of Multinuclear Measurement

    5 MULTINUCLEAR MEASUREMENT OUTLINE OF MULTINUCLEAR MEASUREMENT The solid high-resolution NMR measurement method of rare spin systems ( Cd, and others) of nuclear spins 1/2 is widely used for the structural analysis of materials. Especially, the C nucleus is an indispensable nucleus to analyze the poly- meric material, and various measurement techniques have been developed.

  • Page 48: Method Of Measuring Rare Spin Nucleus Of Spin 1/2

    5 MULTINUCLEAR MEASUREMENT METHOD OF MEASURING RARE SPIN NUCLEUS OF SPIN 1/2 Since a rare spin system is easy to treat due to its small interaction compared with other nuclei, it is the kind of nucleus most generally measured using the solid-state NMR. Be- cause these nuclei are spin 1/2, there is no nuclear quadrupole interaction.

  • Page 49: Method Of Measuring Nucleus Of Spin 1

    5 MULTINUCLEAR MEASUREMENT METHOD OF MEASURING NUCLEUS OF SPIN 1 For a nucleus whose nuclear spin is 1 and asymmetry parameter η is nearly equal to zero, a high-resolution spectrum is obtained by MAS. The asymmetry parameter is the pa- rameter showing the asymmetry of the electric field gradient around the nucleus.

  • Page 50: Measurement Of Relaxation Time

    MEASUREMENT OF RELAXATION TIME OUTLINE OF RELAXATION-TIME MEASUREMENT......... 6-1 RELAXATION TIME MEASUREMENT BY DIRECT MEASUREMENT....................6-2 RELAXATION TIME MEASUREMENT OF C BY TORCHIA METHOD ......................6-4 MEASUREMENT OF T IN THE ROTATING FRAME) ......6-5 ρ RELAXATION TIME MEASUREMENT OF H BY INDIRECT OBSERVATION USING CP METHOD ............

  • Page 51: Outline Of Relaxation-Time Measurement

    6 MEASUREMENT OF RELAXATION TIME OUTLINE OF RELAXATION-TIME MEASUREMENT The relaxation time of a solid sample has useful information about the molecular motion of the specific site. Also, for optimizing the measurement parameters or performing the quantitative measurement, it is necessary to measure the exact relaxation time of each peak in advance.

  • Page 52: Relaxation Time Measurement By Direct Measurement

    6 MEASUREMENT OF RELAXATION TIME RELAXATION TIME MEASUREMENT BY DIRECT MEASUREMENT For the sample that can be measured by a single pulse to obtain the NMR spectrum, you can perform the relaxation-time measurement by direct observation without using CPMAS. There are two methods of relaxation-time measurement by direct observation. •...
  • Page 53 6 MEASUREMENT OF RELAXATION TIME Arrow buttons Fig. 6.1 Set interval window Click the Set Value button. The array parameter window closes, and the values you set are entered into tau_interval in the Experiment Tool. Click the Submit button. The measurement starts. Although the data-processing procedure is the same as that for the inversion-recovery method, use the following approximation formulas.
  • Page 54 6 MEASUREMENT OF RELAXATION TIME RELAXATION TIME MEASUREMENT OF C BY TORCHIA METHOD One technique for measuring the relaxation time of a solid sample is the Torchia method. The relaxation time is obtained by measuring the differences between the spectra by the inversion-recovery method using CP and the spectrum by the CPMAS method.

  • Page 55: Measurement Of T

    6 MEASUREMENT OF RELAXATION TIME MEASUREMENT OF T IN THE ROTATING FRAME) ρ in the rotating frame) is measured by using CPMAS. For the T measurement of ρ ρ C, after transferring the excited magnetization by the CP method, the T is measured by ρ...

  • Page 56: Relaxation Time Measurement Of 1 Ρ

    6 MEASUREMENT OF RELAXATION TIME RELAXATION TIME MEASUREMENT OF H BY INDI- RECT OBSERVATION USING CP METHOD In the solid-state NMR, when measuring the relaxation time of the H nucleus, indirect observation can be performed using the CP method. When the spectrum of H is broad and cannot be observed directly, or when the sample consists of many elements, this in- direct observation method is effective.

  • Page 57: Mqmas Method

    MQMAS METHOD Nuclei having a half-integer spin have quadrupolar interactions that do not exist in nu- clei with a nuclear spin 1/2. Therefore, MAS by itself usually cannot obtain a high- resolution spectrum, and the MAS data cannot be used for the analysis of a compli- cated compound.

  • Page 58: Outline Of Mqmas Method

    7 MQMAS METHOD OUTLINE OF MQMAS METHOD The MQMAS method was proposed by Frydman and Harwood in 1995. Reference: A.Medek, J.S.Harwood, and L.Frydman. JACS, 117, 12779-12787 (1995). The MQMAS method has the advantage that it can eliminate quadrupolar interaction without using a special probe in contrast to the DOR and DAS methods. Moreover, since it can be adjusted comparatively easily, it can be generally used as the measuring method.
  • Page 59 7 MQMAS METHOD As seen in the above spectra, for the spectrum that cannot be analyzed using only the MAS spectrum, measuring with MQMAS can obtain information on the three different sites. Moreover, the MQMAS spectrum shows the MAS spectrum along the direct obser- vation axis and the isotropic spectrum along the evolution (indirect observation) axis.

  • Page 60: Principle

    7 MQMAS METHOD PRINCIPLE The MQMAS method is the technique for controlling magnetization transfer by the pulse sequence and the phase cycling. Here, the two typical MQMAS methods are explained. ■ 3QMAS method The most fundamental pulse sequence in the current MQMAS method and the pathway of magnetization transfer are shown below.
  • Page 61 7 MQMAS METHOD RF Pulse Coherence Order Fig. 7.4 The pulse sequence of the 3QMAS with the Z filter, and magnetization transfer pathway In the 3QMAS with the Z filter, the spin system is excited to 3 quantum by the first pulse in the same way as with the usual 3QMAS, and evolved during time t1 by using phase cycling in which only 3-quantum coherence remains.

  • Page 62: Adjustment

    7 MQMAS METHOD ADJUSTMENT Here the 3QMAS with the Z filter measurement is explained as an example because it is most commonly used. 7.3.1 Adjustment of Power Two power levels are used in the MQMAS measurement with the Z filter. They are the high output power level used to excite the multiple-quantum coherence and the power level for the selective excitation of the Z filter.

  • Page 63: Adjustment Of Parameters

    7 MQMAS METHOD ■ Adjustment of the selective excitation pulse The pulse for the Z filter uses the power of selective excitation. Select the RF intensity so that the 90 ° pulse of the target sample may be 12 to 15 μ s. Adjustment of the pulse width is performed for the highest signal intensity in the same way as the adjustment of the high-power output pulse.
  • Page 64 7 MQMAS METHOD Enter suitable values in scans. In the MQMAS measurement, since the sensitivity is poorer than with a single-pulse measurement, you need to increase the number of scans to accumulate. Also for the 3QMAS measurement using 3-quantum coherence, set the number of scans to mul- tiples of 6 times the integral number.

  • Page 65: Measurement

    7 MQMAS METHOD MEASUREMENT Use the pulse sequence prepared for the MQMAS measurement. For the 3QMAS with the Z filter, you can use the sequence 3qmas_z.jxp. For measurement parameters, copy the parameters that are obtained by the adjustment in Sect. 7.3 and use them to perform the measurement.

  • Page 66: Processing

    7 MQMAS METHOD PROCESSING In the MQMAS method, since it is necessary to perform the shearing process for the data Sect. 7.6.1), you need to divide the data into echo and anti-echo components during the data processing. The flow of MQMAS processing is shown below. a) F2 axis Fourier transform b) F2 axis phase correction c) PN conversion...
  • Page 67 7 MQMAS METHOD Close the window after performing phase correction of the F2 axis. The phase of the F2 axis is applied to nD Processor. Cut the value of the phase of the F2 axis as follows. Highlight the phase: -- : -- : -- line , and press the Cut button.
  • Page 68 7 MQMAS METHOD Set the phase of F2 axis. Highlight transpose, and click the Paste button. The phase correction that was cut in step 3 is added. Perform phase correction of the F1 axis. Click the 2D Phase button, and perform phase correction of F1 axis in the open window.

  • Page 69: Appendix

    7 MQMAS METHOD APPENDIX This section describes special processing required in the MQMAS method. 7.6.1 Shearing process Since the MQMAS method measures the echo, the top of the echo signal (the starting point of FID) shifts along with the t1 evolution time. As an example, a two-dimensional FID signal of the Na nucleus in sodium sulfate (Na ) is shown below.

  • Page 70: Scaling Processing

    7 MQMAS METHOD Thus, you can see that the shift of the sampling starting position of an echo signal causes the first order phase shift. The shearing process makes this phase shift disappear. In data processing of MQMAS, after using PN conversion to divide the data into echo and anti-echo components, the shearing process in the opposite direction is performed on each component.

  • Page 71: Index

    INDEX Ｃ Ｓ CM Decoupling ........3-15 SPINAL64 Decoupling ....... 3-14 CROSS POLARIZATION..... 2-5 SWf-TPPM Decoupling ...... 3-15 Cross-Polarization (CP) ......2-5 Ｔ CW (Continuous Wave) Decoupling....... 2-3, 3-13 TPPM ..........3-13 TPPM (Two Pulse Phase Ｄ Modulation) Decoupling ....2-3 DAS (Dynamic Angle Spinning)..

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