Search of “chlorophyll forms” in vivo by non‐linear laser spectroscopy

Abstract

Induction of a non‐linearity in the long‐wavelength part of the S0 —S1 absorption band of chlorophyll in vivo by a monochromatic pulse results in a simultaneous band shape change in the whole range of investigation (645 – 680 nm). Such homogeneous broadening behaviour at least for time periods ⩾0.5 ns (pulse duration) does not support the hypothesis of many small sub‐bands representing “chlorophyll forms”. The band shape changes at different excitation intensities indicate two excited state absorptions of antenna chlorophyll.

Nonlinear polarization spectroscopy in the frequency domain of light-harvesting complex II: absorption band substructure and exciton dynamics

“…As indicated in Table 2, the T2 values for the subbands of the trimers show an increase from the short wavelength bands to the red-shifted ones, indicating that the rhom values of the subbands are different. This is in conflict with the nearly constant FWHM in the model of Jennings et al (1993), but consistent (especially for the broad FWHM of the band centered at 649 nm) with earlier nonlinear laser spectroscopic results (Leupold et al, 1989).…”

“…Recent ideas converge toward a consensus model in which at least six Chl forms are assumed to describe steady-state spectra of LHC II (Jennings et al, 1993). An earlier approach to the problem by means of nonlinear laser spectroscopy has been reported by Leupold et al (1989). Induction of nonlinear absorption in the long-wavelength part of the Qy-absorption band of chloroplast suspensions (by highly monochromatic sub-ns pulses at 687 and 692 nm) resulted in transient band-shape changes in the whole range of investigation (645-680 nm).…”