TY - JOUR
T1 - SIMULTANEOUS MEASUREMENT OF ABSORPTION AND CIRCULAR DICHROISM IN A SYNCHROTRON SPECTROMETER.
AU - Sutherland, John Clark
AU - Keck, Peter C.
AU - Griffin, Kathleen Pietruszka
AU - Takacs, Peter Z.
N1 - Funding Information:
We are gratefult o Robert Madden, David Ederera nd the staffa t SURF whosec ooperation madet hiswork possibleW. e thankD r ReginaM . Santellaa nd Dr I. BernardW einsteinC, olumbia Universityf,o r the sampleo f the dG-BP the ab-sorptiona ndCD spectrao f whicha rer ecordeidn fig. 2. Researchsu pportebdy the US Department of Energya nd a ResearchC areerD evelopment Award from the National Cancer Institute, DHHS(CA00465)t o JCS. SURF is operatedb y the NationalB ureauo f StandardsU, S Dept. of Commerce.
PY - 1981/1/1
Y1 - 1981/1/1
N2 - We describe a method for simultaneously measuring the absorption spectrum and circular dicroism (CD) of a sample in a spectrometer that employs a transparent window photomultiplier detector. During the spectral scan, the computer control system simultaneously monitors the CD signal, the high voltage applied to the detector and the current in the storage ring. A servo-control system maintains the detector current at a constant value during the scan by varying the applied high voltage. The logarithm of the photomultiplier gain is calculated from the value of the high voltage using the predetermined characteristics of the tube. The gain value is corrected for the decrease of the storage ring current with time. During a single spectral scan, the computer generates a pseudo-absorption spectrum, which is the sum of the absorbance of the sample and of various wavelength-dependent system parameters. An absolute absorption spectrum is produced when the pseudo-absorption spectrum of a "blank" sample is subtracted from the desired sample spectrum. Absorption spectra measured by this method agree with spectra obtained with a double-beam spectrophotometer.
AB - We describe a method for simultaneously measuring the absorption spectrum and circular dicroism (CD) of a sample in a spectrometer that employs a transparent window photomultiplier detector. During the spectral scan, the computer control system simultaneously monitors the CD signal, the high voltage applied to the detector and the current in the storage ring. A servo-control system maintains the detector current at a constant value during the scan by varying the applied high voltage. The logarithm of the photomultiplier gain is calculated from the value of the high voltage using the predetermined characteristics of the tube. The gain value is corrected for the decrease of the storage ring current with time. During a single spectral scan, the computer generates a pseudo-absorption spectrum, which is the sum of the absorbance of the sample and of various wavelength-dependent system parameters. An absolute absorption spectrum is produced when the pseudo-absorption spectrum of a "blank" sample is subtracted from the desired sample spectrum. Absorption spectra measured by this method agree with spectra obtained with a double-beam spectrophotometer.
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U2 - 10.1016/0029-554X(82)90803-5
DO - 10.1016/0029-554X(82)90803-5
M3 - Article
AN - SCOPUS:10244267030
SN - 0029-554X
VL - 195
SP - 375
EP - 379
JO - Nuclear Instruments and Methods
JF - Nuclear Instruments and Methods
IS - 1-2
T2 - Proc of the Natl Conf, 2nd
Y2 - 15 July 1981 through 17 July 1981
ER -