Polarization of fluorescence of polymethine dyes in solutions with various viscosities

Воропай, Е. С.; Popechits, V. I.; Самцов, М. П.

doi:10.1007/bf00660580

Cited by 1 publication

(1 citation statement)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, there are no transitions connected only with the terminal fragments without involvement of the AO of the polymethine For example, MOs formed by AO of terminal fragments but with a contribution of C AO of the polymethine chain participate in formation of S 2 (ππ * ) states. The calculations agree with conclusions that were made earlier based on experimental investigations of the nature of the short-wavelength absorption bands and polarized spectra of symmetric PD [32]. It should be noted that the energy gap between separate electronic states decreases as the energy of the electronically excited states increases.…”

Section: Resultssupporting

confidence: 86%

Optical properties of new indotricarbocyanine dye as a limiter of laser radiation power

et al. 2007

Self Cite

View full text Add to dashboard Cite

We present results of experimental and theoretical studies of the optical characteristics of a new indotricarbocyanine dye that is capable of effectively limiting the power of laser radiation in the visible spectral range. The spectral-luminescent and energy characteristics of the dye molecules and their absorption spectra from the excited state with nanosecond resolution are investigated experimentally. Quantum-chemical methods are used to calculate electronic absorption spectra from the ground (S 0 → S n ) and excited (S 1 → S n ) states and to determine the nature of electronic states of the molecule and the rate constants of intramolecular photophysical processes. The results of the theoretical research agree with experimental data. It is shown that the investigated dye has singlet-singlet absorption at 400-600 nm. Nonlinear absorption of the dye upon excitation by radiation of the second harmonic of a Nd:YAG laser is studied by z-scanning with an open diaphragm. The ratio of dye absorption cross sections from the excited and ground states at 532 nm is determined in the framework of a three-level model. The results are compared with those for previously studied compounds.Introduction. Polymethine dyes (PD) are broadly used in various branches of science and technology, e.g., in the photographic industry as photosensitizers [1], in biology and medicine as fluorescent markers and materials for photochemotherapy [2][3][4], in solar cells [5][6][7] and quantum electronics as passive gates, active media for tunable lasers, and nonlinear materials [8-10], etc. Recently the nonlinear optical properties of PD [11][12][13][14][15] have become especially interesting due to the search for new nonlinear materials for application as limiters of laser radiation power (nonlinear limiters) in the visible spectral region [13,16,17]. The properties of nonlinear optical materials based on organic dyes must satisfy several requirements in order to be highly efficient [18][19][20][21]. A high attenuation coefficient for laser radiation is one of the main parameters for optical limiters. In addition, there must be a low threshold and activation time, a broad dynamic range, high linear transmission in a broad spectral range, and, finally, a long operational lifetime for the active medium. PD in solutions satisfy most of these requirements. Therefore, the search for molecular structures in this class of organic molecules and comprehensive investigations of the optical properties of the most promising compounds used as the active medium of limiters are extremely timely.The limiting properties of solutions of the indotricarbocyanine dye 2-{7-[1,3,5-trimethyl-3-ethyl-2-(1H)-indoliniden]-4-chloro-3,5-trimethylene-1,3,5-heptatrien-1-yl}-1,3,5-trimethyl-3-ethylindolium perchlorate (PD 7098) were previously studied upon excitation by nanosecond pulses of second harmonic radiation from a Nd:YAG laser (532 nm) [21]. Quantum-chemical calculations and experimental investigations of the photophysical properties of this dye were carried out in o...

show abstract

Section: Resultssupporting

confidence: 86%