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61.
62.
P. F. Heelis B. J. Parsons G. O. Phillips C. Barghigiani ‡ G. Colombetti ‡ F. Lenci ‡ J. F. McKellar ‡ 《Photochemistry and photobiology》1979,30(4):507-512
Abstract— –The spectroscopic properties of riboflavin tetrabutyrate have been studied in lecithin lipo-somes and several detergent micellar systems. The results indicate that the flavin chromophore is located close to the liposome-water interphase rather than in the hydrophobic region. By varying the number of flavins contained in each liposome and employing fluorescence spectroscopy and steady state photolysis techniques, the possible existence of two distinct environments for the flavin chromophore was demonstrated. Several basic photochemical properties of riboflavin tetrabutyrate in liposomes and micellar systems were investigated using laser flash and microsecond flash photolysis techniques. 相似文献
63.
Brookes MD Xia C Tang J Anstey JA Fulsom BG Au Yong KX King JM McKellar AR 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2004,60(14):629-3242
The design and operation of an apparatus for studying infrared spectra of weakly-bound complexes is described in detail. A pulsed supersonic jet expansion is probed using a tunable Pb-salt diode laser spectrometer operated in a rapid-scan mode. The jet may be fitted with either pinhole or slit shaped nozzles, the former giving lower effective rotational temperatures, and the latter giving sharper spectral lines. Notable features of the apparatus include use of a toroidal multi-pass mirror system to give over 100 passes of the laser through the supersonic jet, use of the normal laser controller for laser sweeping during both setup and data acquisition, and use of a simple semi-automated wavenumber calibration procedure. Performance of the apparatus is illustrated with observed spectra of the van der Waals complex He-OCS, and the seeded helium clusters He(N)-OCS and He(N)-CO. 相似文献
64.
P. F. Heelis B. J. Parsons G. O. Phillips J. F. McKellar † 《Photochemistry and photobiology》1979,30(3):343-347
Abstract— Primary and secondary photochemical processes in oxygen-free aqueous solution have been characterised for FMN alone and in the presence of EDTA and four amino acids using nanosecond and microsecond flash photolysis and continuous photolysis techniques. The relative contributions of oneelectron and two-electron (group or hydride transfer) reactions to the deactivation of the triplet has been determined by comparing the radical concentration (560 nm) with the bleaching of the ground state (446 nm). It was concluded that one-electron reactions (hydrogen atom or electron abstraction) are the major mode of reactivity of the flavin triplet state with all the suhstrates studied.
The nature of the reactions of the flavin semiquinone radical have been studied quantitatively by microsecond flash photolysis. These secondary reactions consist of either a 'back reaction' between the flavin and substrate radicals (tryptophan or glycyl-tyrosine) or the transfer of a second electron (or hydrogen atom) from the substrate radical to the flavin radical (EDTA, methionine and possibly cysteine) to form reduced flavin and oxidised substrate. From a comparison of the quantum yields of formation of reduced flavin using 'flash' and continuous irradiation, an additional pathway for the decay of the flavin radical is suggested to occur at low light intensities in the presence of glycyl-tyrosine or histidine. 相似文献
The nature of the reactions of the flavin semiquinone radical have been studied quantitatively by microsecond flash photolysis. These secondary reactions consist of either a 'back reaction' between the flavin and substrate radicals (tryptophan or glycyl-tyrosine) or the transfer of a second electron (or hydrogen atom) from the substrate radical to the flavin radical (EDTA, methionine and possibly cysteine) to form reduced flavin and oxidised substrate. From a comparison of the quantum yields of formation of reduced flavin using 'flash' and continuous irradiation, an additional pathway for the decay of the flavin radical is suggested to occur at low light intensities in the presence of glycyl-tyrosine or histidine. 相似文献
65.
P. F. Heelis B. J. Parsons G. O. Phillips J. F. McKellar † 《Photochemistry and photobiology》1978,28(2):169-173
Abstract— Primary photochemical processes in aqueous solution have been characterised for FMN. The influence of pH on these processes is attributed to protonation of the neutral triplet and not to the presence of a dimeric species as postulated earlier. Second order rate constants for reaction between the neutral triplet and some naturally occurring amino acids are reported. 相似文献
66.
McKellar AR 《The Journal of chemical physics》2008,128(4):044308
High resolution spectra of (4)He(N)-CO(2) clusters are studied in the region of the CO(2) nu(3) fundamental band (approximately 2300 cm(-1)). The clusters are produced in a pulsed supersonic jet expansion from a cooled nozzle source and probed by direct absorption using a tunable diode laser operating in a rapid-scan mode. Four carbon dioxide isotopes ((16)O(12)C(16)O, (16)O(13)C(16)O, (18)O(13)C(18)O, and (16)O(13)C(18)O) are used to support the analysis, and because additional rotational transitions are allowed for the asymmetric one ((16)O(13)C(18)O). Resolved R(0) (J=1<--0) rotation-vibration transitions are observed for clusters up to N=60. A detailed rotational analysis is possible up to N approximately 20 and, with some assumptions, to N approximately 37 and beyond. The derived rotational constants (B values) vary smoothly with N and show evidence for broad oscillations similar to those already reported for He(N)-OCS and He(N)-N(2)O. Possible indications of a disruption are observed in the J=2 levels of larger clusters (N>22) which could be caused by interactions with a "dark" helium cluster modes. 相似文献
67.
The ν2 (CO stretch) fundamental band of formyl fluoride (HFCO) was studied in the region 1800 to 1910 cm?1 using the two techniques of intracavity CO laser Stark spectroscopy at sub-Doppler resolution and Fourier transform spectroscopy at Doppler-limited resolution. Accurate values of the molecular parameters of the ground and excited (v2 = 1) vibrational states were obtained from a combined fit of the ν2 band data and available microwave data. The results include precise determinations of the electric dipole moment components (μa and μb) of HFCO in the ground and excited states. 相似文献
68.
69.
N. Hunt S.C. Foster J.W.C. Johns A.R.W. McKellar 《Journal of Molecular Spectroscopy》1985,111(1):42-53
The spectrum of OCS with natural isotopic abundances has been measured in the 1975- to 2140-cm?1 region with near-Doppler-limited resolution using a Fourier transform spectrometer. Sixteen bands have been analyzed, including the following five bands for the first time at high resolution:
16O13C32S | 1000-0000 | 2009.228 cm?1 |
16O13C32S | 1110-0110 | 2002.427 cm?1 |
18O12C32S | 1000-0000 | 2026.147 cm?1 |
16O12C32S | 0400-0000 | 2104.828 cm?1 |
16O12C32S | 0510-0110 | 2115.169 cm?1 |