The Raman spectra offluoroorganic compounds show specific emission bands for carbon-fluorine bonds in the range 500-800 wave numbers (car'). With very limited exceptions, biological materials do not contain carbon-fluorine bonds. Fluoroorganic compounds introduced into biological samples can be detected by a Raman emission signal.Normal mode C-F bond bands are observed: (1) at 710-785 cm for trifluoromethyl groups;(2) at 530-610 cm' fbr aromatic organofluorine bonds; (3) a range centered at 690 cm1 for difluoromethylene groups. Specific examples of normal mode C-F bond emissions for organofluorine compounds containing trifluoromethyl groups are: 1-bromopertluorooctane, 726 cm' ; perfiuorodecanoic acid, 730 cm' ; triperfiuoropropylamine, 750 cm' ; 1,3,5-ths-(trifiuoromethyl)-benzene, 730 cm; Fluoxetine (Prozac) commercial powdered pill at 782 cm1 . Compounds containing aromatic C-F bonds are: hexafiuorobenzene, 569 cm' ; pentafluoropyridine, 589 cm . Difluoromethylene groups: perfiuorodecalin, 692 car1; perfiuorocyclohexane, 691 car1Raman spectra were observed with a standard single monocbromator. The 510.8 nm light source was a copper-vapor laser operated at 3-10 watts with 10-12 nanosecond pulses at 10 kHz repetition rate. Detection was made with a time-gated photomultiplier tube. Resonance Raman spectra were also observed at 255.4 nm using a frequency doubling crystal. Observed spectra were free offluorescence with very sharp strong C-F lines.
The results of Raman and fluorescence spectra investigations of fluoroorganic aromatic compounds are presented. We present technique for realizing of qualitive and quantitive analysis of fluoroorganic aromatic compounds on the base of Raman and fluorescence spectroscopy. We propose to applicate the pulsed copper vapor laser for exciting of Raman and fluorescence spectra of fluoroorganic samples. The Raman spectra have been received for a number of compounds as: 1 -bromoperfluorooctane, perfluorodecanoic acid, 1 ,3 ,5-trifluoromethylbenzene, hexafluorobenzene, pentafluoropyridine, p-fluoro-DL-phenyl-alanine, m-fluoro-DL-phenylalanine, o-fluoro-DL-phenyl-alanine, m-fluoro-DL-tyrosine, 6-fluoro-DL-tryptophan, 5-fluorouracil, 5-Fluorouridine ,5-fluoroindole.on the base of our measurements we have worked out the manner of linear molecule CnF2n+1 Br length recognizing.Thus, presented technique, based on using of the modem laser sources and registration system of Raman and fluorescence spectra, permitted to identify the different fluoroorganic molecules in mixtures and pure samples.
Spectroscopic method of zigzag chain molecules length determination from Raman spectra was developed. The method is based on measuring Raman lines frequencies, corresponding to acoustical modes and different optical modes of chain molecules. The excitation of Raman spectra was produced by continuous argon laser or by pulsed radiation from copper vapor laser. Raman spectra of hydrocarbon and fluorocarbon zigzag structure molecules have been studied. The investigations have been fulfilled for following substances: C n H 2n+2 (n=6, 7, 10), C n F 2n+1 Br (n=6,7,8, 10, 14), C n F 2n+2 , C n H 2n O 2 (n=4, 5, 8, 10, 11, 13, 15, 18). The frequency dependence of some Raman modes on the length of zigzag molecule has been observed. The theory, explaining this dependence, is developed. The obtained results allow estimating fluorocarbon and hydrocarbon molecules length from the Raman spectra parameters.
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