Environment and Site Survey Measurement
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H157655_1_008
7.3.4.2
Most Commonly Studied Nuclei
Nuclei
NMR Frequency (MHz)
Magnets
400
500
600
700
1H
400.000
500.000
600.000
700.000
2H
61.422
76.773
92.124
107.474
11B
128.378
160.462
192.546
224.630
13C
100.613
125.758
150.903
176.048
15N
40.560
50.697
60.834
70.971
19F
376.498
470.592
564.686
658.780
27AI
104.261
130.318
156.375
182.432
29Si
79.495
99.362
119.229
139.096
31P
161.976
202.456
242.937
283.418
Table 7.7:
List of Most Commonly Studied Nuclei and Corresponding Resonance Frequencies
7.3.4.3
Guidelines for HF Interference
As a general guideline the level of any HF interference should be less than an electrical field
strength (detection: max. peak) of 80 dBuV/m with a minimum Resolution Band Width (RBW)
of 300 kHz at the side of the magnet.
7.3.4.4
Reducing HF Interference
Screening a site for possible HF Interference is complicated and expensive. Shielding of the
laboratory with a Faraday cage is a possible solution, though having to take such measures
is quite rare.
When designing and manufacturing the Bruker spectrometers, care is taken to provide
adequate shielding and the instruments rarely suffer from interference in normal HF
environments. Furthermore, the advanced BSMS digital lock system - included with all Bruker
AVANCE spectrometers - allows a shift in the 2H lock frequency with certain limits. This may
allow enough variation in the absolute magnet field strength to shift the NMR signal away
from that of local broadcasting frequencies.
HF interference may occur between two or more spectrometers located in close proximity
and operating at the same nominal 1H resonance frequency. These problems can be avoided
by energizing the different magnets at slightly different fields, such that their operational
frequencies are separated by ~ 200 kHz at the nominal 1H resonance frequency.
Содержание AVANCE
Страница 6: ...Contents vi H157655_1_008 ...
Страница 24: ...System Components 24 H157655_1_008 ...
Страница 32: ...Magnet Access and Rigging 32 H157655_1_008 ...
Страница 38: ...Ceiling Height Requirements 38 H157655_1_008 ...
Страница 42: ...Magnetic Stray Fields 42 H157655_1_008 6 3 Stray Field Plots Figure 6 1 Example of a Stray Field Plot ...
Страница 72: ...Utility Requirements 72 H157655_1_008 ...
Страница 82: ...Floor Plan 82 H157655_1_008 ...
Страница 96: ...CryoProbe and Other Accessories 96 H157655_1_008 ...
Страница 102: ...Contact 102 H157655_1_008 ...
Страница 104: ...List of Figures 104 H157655_1_008 ...
Страница 109: ...H157655_1_008 109 ...
Страница 110: ...Bruker Corporation info bruker com www bruker com Order No H157655 ...