TRANSIENT RAMAN-SPECTROSCOPY OF N-15-SUBSTITUTED BACTERIOCHLOROPHYLL-A - AN EMPIRICAL ASSIGNMENT OF T1 RAMAN LINES

N-15-substituted bacteriochlorophyll a (BChl a) was extracted from the cells of Rhodobacter sphaeroides 2.4.1 grown in a medium containing N -15-ammonium sulfate and yeast concentrate. The T1 Raman spectra of N- 14- and N-15-BChl a were obtained as the difference spectra of high-po wer minus low-power one-color, pump-and-probe measurements using 420 n m, 5 ns pulses. A set of empirical assignments of the T1 Raman lines w as made, based on shifts upon N-14 --> N-15 substitution. The S0 Raman spectra of the two BChls were also obtained by using the 457.9 nm cw beam, and a set of assignments of the S0 Raman lines was given for com parison.