Transient Absorption of Organic Molecules under High-Power Laser Excitation

Abstract

In the present work, results of investigations into the transient absorption of some organic compounds by the method of pulsed flash photolysis are given. Experimental investigations were carried out using an original setup of pulsed flash photolysis with an exciting pulse of XeCl-laser radiation of nanosecond duration and sensing by broadband laser-transient fluorescent radiation of a mixture of organic fluorophors called "white light" excited by the same source in the wavelength range 330-750 nm. The setup registers the short-living (singlet-singlet) and long-living (triplet-triplet) absorptions. The transient absorption spectra of already investigated para-terphenyl, naphthalene, and 1-phenyl-2(2-naphthyl)-ethylene molecules are presented; the spectra of the transient absorption and its nature are in good agreement with the experimental and calculated data published in the literature. We first investigated the transient absorption of LOC1 (S 1 -S n at 580 nm and T 1 -T n at 500 nm) and phenalemine 512 (S 1 -S n at 395 nm). It is demonstrated that the experimentally observed induced absorption of phenalemine 512 and PD 789 is the S 1 -S n absorption, which is in good agreement with the results of quantum-chemical calculations.

Two-Photon Absorption in Rhodamine 6G Occurring in Concert with Fluorescence Depletion

“…This process is known as a multiple-excitation process or photo-cyclic process. [6][7][8] The molecule is first excited to a higher state by irradiating it with the erase beam, which is followed by the excited molecule diffusing thermal energy in the matrix host, and finally relaxing back to the ground state. In some cases, the erase beam with a high photon energy causes a photo-ionization process from these excited states.…”

Spectral and luminescent properties of sensitizers based on psoralen substitutes

“…In addition to the theoretically calculated absorption and fluorescence spectra of psoralen, 21,22-dimethyl-10,11-cyclohexylpsoralen (DCPs), and 10,11-phenyl-21,22-cyclohexylpsoralen (PCPs), the spectra were measured with an SM-2203 spectrofluorimeter. A laser flashphotolysis setup [10] was used to measure the DCPs and PCPs transit absorption spectra with nanosecond time resolution.…”

Formation of p-terphenyl excited states in the ionic liquid methyltributylammonium bis[(trifluoromethyl)sulfonyl]imide: pulse radiolysis study

“…All of them have absorption spectra in a similar region [37][38][39] (see Table 1). The presence of 80 mM BP can simplify the interpretation of expected transient spectra.…”

“…From the experiments with TP as the sole component present in R 4 NNTf 2 solvent (the results of the radiolysis of TP in IL will be the subject of separate publication) and literature data concerning 3 TP* absorption [38,39], there are strong indication that the triplet state of p-terphenyl 3 TP* is responsible for the intermediate absorption with maximum at 450 nm.…”