F. Adamec

HOLE-BURNING SPECTROSCOPY OF ACTIVE AND INACTIVATEE) PHOTOSYSTEM II PARTICLES

This paper reports transient and persistent hole‐burning of photosynthetically active as well as chemically reduced and heat inactivated photosystem II particles isolated from cyanobacteria. Transient spectra of active and non‐active particles are significantly different. For both, the possible origin of the bottle‐neck state is discussed. Persistent holes were ascribed to the antenna complex of photosystem II. From their width the energy transfer rate was estimated to be 4.8 ps at 4.2 K.

Spectral hole burning of photosynthetic antenna of blue-green algae

Photosystem II core antenna of blue-green algae Synechococcus isolated in gel was studied by optical hole burning spectroscopy at 4·2 K. Persistent holes were burned into fluorescence spectra throughout the region 680–696 nm. The hole width extrapolated to zero burning fluence yielded a value 1·0±0·2 cm−1. A theoretical interpretation of the hole profile in fluorescence is presented. The dependence of saturated hole depth on burning wavelength is related to inhomogeneous site distribution function.

Site directed study of excited energy transfer in photosynthetic antenna by hole burning in fluorescence spectra

Abstract High spectral selectivity of hole burning in fluorescence spectra was used to study excited energy transfer in the CP 43 chlorophyll-protein complex of core antenna of photosystem II of Synechococcus . The observed energy transfer time is 7.6 ± 1.1 ps. The phenomenon of laser-induced hole filling was studied and explained in terms of energy transfer within the CP 43 complex.

Influence of water stress on photosynthesis and variable chlorophyll fluorescence of potato leaves

Net photosynthetic rate (PN), productivity and the first phases of the fluorescence induction curve were investigated in leaves of two potato cultivars exposed to water stress. Water stress applied to potato plants at the beginning of their development (planting-bud formation) increased productivity but decreased PN and variable fluorescence (Fv) of leaves. The short-term influence of water stress on the same plants also diminished the Fv.

Spectral hole burning study of photosynthetic antenna pigment-protein complexes

Abstract Results of persistent spectral hole burning in fluorescence spectra of photosystem II core antenna complexes CP 43 and CP 47 are presented. The holewidths (extrapolated to zero burning fluence) yield the excited state population decay times T 1 which are influenced by fast energy transfer within the antenna complexes. The obtained T 1 values range between 6.6 and 10 ps. The holewidths are independent on temperature within the studied temperature interval 1.5-4.2 K. The observed phenomenon of laser-induced hole filling in the spectra of CP 43 is explained in terms of energy transfer within the CP 43 pigment-protein complex.

Structure and function of photosynthetic systems studied by hole burning spectroscopy

Abstract Persistent and transient fluorescence hole-burning spectra of both higher plants and blue-green algae were measured to study the role of structural and functional properties of photosynthetic materials prepared by means of different biochemical methods: intact cells, thylakoide membranes, photosystem II particles and isolated antenna pigments. The width of persistent zero-phonon hole was interpreted due to fast excited energy transfer in antennae. The unstructured transient holes observed on reaction centres of photosystem II particles are connected with a charge-separated bottle-neck.

Spectral properties of antenna pigment—protein complexes studied by hole-burning spectroscopy

Abstract Persistent spectral hole-burning fluorescence spectra of photosystem II core antenna at 4.2 were measured. The obtained hole widths were interpreted in terms of fast excited energy transfer within pigment-protein complexes. The energy transfer efficiency, the inhomogeneous distribution function and hole-burning mechanism are discussed with respect to the role of the surrounding protein environment (polymer, glass). The observed light induced hole filling is also interpreted as a result of efficient energy transfer.

Luminescence and nonlinear optical properties of porous silicon

Abstract We observe a blue shift of the porous silicon photoluminescence peak with decreasing temperature in the range 305-180 K. Further, we study two-photon absorption (TPA) in porous silicon at 300 K through the luminescence excitation spectrum. The TPA shows an exponential tail with onset at 2hv ≈ 2.4 eV. This shape can be ascribed to potential fluctuations.

Role of central metal in phthalocyanine Langmuir-Blodgett films studied by hole burning

Abstract The persistent spectral hole burning technique was applied to the fluorescence spectra of free base tetra-4- tert -butyl phthalocyanine and chlor-aluminium tetra-4- tert -butyl phthalocyanine multilayer Langmuir-Blodgett films. Resonant zero phonon holes were burnt into the O-O fluorescence band near 700 nm at 4.2 K. A set of red shifted off-resonant holes is explained as due to localized molecular vibrational states. For both free base and central metal phthalocyanine Langmuir-Blodgett films the structure of the hole burned spectra indicates a photophysical hole burning mechanism.

Excited energy transfer in Langmuir-Blodgett films studied by hole burning spectroscopy

Abstract The hole burning technique was applied in fluorescence excitation spectra of free base tetra-4-tert-butyl phthalocyanine multilayer Langmuir-Blodgett films. Persistent holes were burnt into the spectral region near 615 nm (attributed to the absorption of domains of parallel molecules) and detected near 700 nm at the OO fluorescence band (attributed to the emission of off-domain molecules in the Langmuir-Blodgett films). The fast excited energy transfer running from the domains to the off-domain molecules results in the decrease of the excited state lifetime and corresponding broadening of the measured holewidth δ HB = 0.25 cm −1 at 4.2 K. The obtained δ HB temperature dependence yielding δ HB (T) = 0.20 + 0.0085T (1.15±0.1) cm −1 is discussed in the frame of the Foerster excited energy transfer model.