Non-Lorentzian zero-phonon holes and new insights on nonphotochemical hole burning: Al-phthalocyanine in hyperquenched glassy water

Abstract

Articles you may be interested inA model for persistent hole burned spectra and hole growth kinetics that includes photoproduct absorption: Application to free base phthalocyanine in hyperquenched glassy ortho-dichlorobenzene at 5 K Electronic dephasing and electron-phonon coupling of aluminum phthalocyanine tetrasulphonate in hyperquenched and annealed glassy films of ethanol and methanol over a broad temperature range Zero-phonon hole ͑ZPH͒ profiles and hole spectra that span about eight decades of burn fluence are reported for Al-phthalocyanine tetrasulphonate in hyperquenched glassy water ͑HGW͒ films at 5.0 K. The profiles of unsaturated zero-phonon holes ͑low burn fluence stage͒ are more sharply tipped than a Lorentzian. It is shown that the non-Lorentzian behavior is a natural consequence of the interplay between the three distributions that govern the dispersive kinetics of nonphotochemical hole growth. They are denoted by , ␣, and , where is the tunnel parameter associated with nonphotochemical hole burning ͑NPHB͒ and ␣ is the angle between the transition dipole and the laser polarization. The distribution stems from off-resonant absorption of the zero-phonon line ͑ZPL͒. The single site absorption spectrum used in the calculations included the ZPL and the phonon sideband. The contribution of a distribution of homogeneous ZPL widths to the non-Lorentzian behavior was assessed and found to be negligible compared to that of the above distributions. The burn fluence dependence of the hole spectra, which include the ZPH, phonon sideband, and antihole structures, leads to new insights on the mechanism of NPHB, ones that necessitate modification of the Shu-Small mechanism ͓L. Shu and G. J. Small, J. Opt. Soc. Am. B 9, 724 ͑1992͔͒. Although that mechanism recognizes the importance of coupling between the intrinsic and extrinsic two-level systems (TLS int ,TLS ext ) of the chromophore/glass system and diffusion of excess free volume triggered by optical excitation, it does not adequately account for the effects of multiple excitations of redshifted ͑relative to the burn frequency B ͒ preburn and antihole sites. The results show that multiple excitations ultimately lead to the entire antihole being blueshifted. A ''second channel'' of hole burning becomes apparent at sufficiently high burn fluences. A model for this channel based on a distribution of extrinsic multilevel systems is proposed.

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…”

“…Roughly, the hole burning yield is sixty to several hundred times lower in protein complexes than in hyperquenched water and organic glasses [34][35][36][37] . This is reasonable, taking into account that the entities experiencing light-induced fluctuations (tunneling) are expected to be larger and heavier in protein than in the case of amorphous host comprised of small molecules.…”

“…According to 13,34,35,38 , in the absence of the energy transfer (this is the case for this manuscript focusing on the lowest-energy states of the complexes) the time dependence of the absorption spectrum affected by SHB can be described with…”

“…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.…”

Single-cell nonphotochemical hole burning of ovarian surface epithelial carcinoma and normal cells

“…where ⍀ exp(Ϫ2 ) represents the phonon-assisted tunneling rate; ⍀ is set to 7.6 ϫ 10 12 s Ϫ1 (10); and , the fluorescence lifetime, was determined to be 1.8 ns at 77 K. The parameters and ␣ each cause a distribution of hole-burning rates that leads to dispersive kinetics, and it has been shown that the distribution is by far the dominant factor for the first 80% of the total burn (8). values for the o parameter allow conclusions to be drawn regarding the relative order of the environment experienced by the chromophore, which in the present case consists of MF680 in the lipid-based mitochondrial membranes.…”