Temperature Dependence of Hole Growth Kinetics in Aluminum−Phthalocyanine−Tetrasulfonate in Hyperquenched Glassy Water

Abstract

The temperature (T) dependence of hole growth kinetics (HGK) data that span more than four decades of burn fluence are reported for aluminum-phthalocyanine tetrasulfonate (APT) in fresh and annealed hyperquenched glassy water (HGW) for temperatures between 5 and 20 K. The highly dispersive HGK data are modeled by using the "master" equation based on the two level system (TLS) model described in 2000 by Reinot and Small [J. Chem. Phys. 2000, 113, 10207]. We have demonstrated that thermal line broadening is not enough to account for temperature-dependent HGK for temperatures greater than 10 K. To overcome the discrepancy, the hole growth model must account for thermal hole filling (THF) processes. For the first time, the "master" equation used for HGK simulations is modified to take into account both the temperature dependence of the (single site) absorption spectrum and THF processes, effectively turning off those TLS which do not participate in the hole burning process at higher temperatures. A single set of parameters, some of which were determined directly from the hole spectra, was found to provide satisfactory fits to the HGK data for APT in fresh and annealed HGW for holes burned in the 679.7-676.9 nm range from the high to low energy sides of the Qx absorption band. Furthermore, we propose that HGK modeling at high burn fluences requires that the TLS model be further modified to take into account the existence of extrinsic multiple level systems.

Parameters of the Protein Energy Landscapes of Several Light-Harvesting Complexes Probed via Spectral Hole Growth Kinetics Measurements

“…As evident from the data presented in Table 1, the parameters of the tunneling distribution observed for photosynthetic protein complexes are significantly different from those reported for hyperquenched glassy water and simple organic glasses [34][35][36][37] . The LH2 antenna complex, which was explored in detail earlier 38 and that contains bacteriochlorophyll a, not chlorophyll a, exhibited parameters in the same range…”

“…At the first glance, prolonged storage at 80C o did not affect the properties of the sample. The hole burning action spectrum and fluorescence spectrum, though, exhibited somewhat larger red shift with respect to earlier-published results 11,37 (although the magnitude of the action spectrum shift appears to be irradiation dose dependent, see below). Concerning the HB action spectrum, we utilized approaches, which are significantly different from those of 11 , where relatively intense burning (0.05 J/cm 2 ) and low read resolution (0.5 cm -1 ) were employed.…”

“…The software was extensively tested with various parameters and it has been confirmed that in case the anti-hole was shifted far away to the blue from the burn wavelength (and thus multiple acts of burning per single molecule were excluded), both programs (employed in this work and that of 36,37 , with perfect spectral memory) yielded identical results. Due to large number of parameters in Eqs.…”

“…Both SHB and single molecule spectroscopy have been applied in the research on low-temperature dynamics and energy barrier distributions of glasses and polymers [31][32][33][34][35][36][37] . In particular, hole growth kinetics (HGK) measurements have been employed in 13,[34][35][36][37] . However, until recently the simulations of the hole burning in PS complexes (e.g.…”

Modeling study of non-line-narrowed hole-burned spectra in weakly coupled dimers and multi-chromophoric molecular assemblies

“…A description of the effects of EET on the measured ZPH action spectrum in photosynthetic complexes has recently been provided by Zazubovich and Jankowiak [20], but important work remains to be done on this subject, particularly concerning the distribution of photoproduct in the post-burn spectrum. At present, the phonon sideband structure (including anti-holes) observed in resonant HB spectra in many photosynthetic complexes is still being fitted with the standard master equation (which was developed to account for the hole shape produced by isolated impurities embedded in glasses [21,22]), while NLN HB spectra have for many years been modeled using simple Gaussian curves [14,23,24]. Since EET can rather significantly alter the observed shapes of both resonant and non-resonant HB spectra (as well as line-narrowed fluorescence spectra), a thorough understanding of these effects is crucial for accurate interpretation of a variety of experimental data, especially the broad photoproduct distributions observed in both resonant and non-resonant HB experiments.…”