Evidence of Superexciplex in Dye Molecules

Abstract

The excited state behavior of dye molecules under intense pulsed laser excitation appears to differ from that under low-power cw Xenon lamp excitation. In the latter case molecules absorb photons (from the lamp), go to the excited state and produce normal fluorescence. This is a one photon-one molecule process. But in the former case, two excited dye molecules combine together to form 'superexciplex' and produce fluorescence and also amplified spontaneous emission (ASE) under intense, sharp, laser pulse excitation. This paper gives sufficient evidence verifying the existence of this new molecular species.

Bichromatic laser emission from dipyrromethene dyes incorporated into solid polymeric media

“…[35][36][37][38][39] Coumarin dyes have also been found to emit amplified spontaneous emission ͑ASE͒ in the form of two distinct narrow bands in certain solvents, with the apparition of the two ASE bands depending on dye concentration and pump power. [40][41][42][43] In this work, we present results on the bichromatic laser a͒ emission from some analogs of the dye PM567 incorporated into solid polymeric matrices. The dependence of this dual emission on different factors is studied, and its origin and causes are discussed.…”

Amplified Spontaneous Emission from the Monomer of a Conjugate Polymer by Energy Transfer Process

“…The same ASE technique has been employed to track the excited-state dynamics of a variety of molecules. 15,16) In our earlier papers, 13,14) it was shown that MEH-PPV produces ASE only from the excimeric state at 600 nm, although the fluorescence peak is at approximately 560 nm. The purpose of this study is to demonstrate a technique that forces the monomer of MEH-PPV to produce ASE.…”

Using a Spectrofluorometer for Resonance Raman Spectra of Organic Molecules

“…In fact, when the Nd:YAG laser (at 532 nm) was used to produce Raman signal from acetone, a sharp signal at 630 nm of FWHM of 1 nm or less was obtained [13,14]; but when Rhodamine dye solution was excited, a broad fluorescence was observed with the peak at 630 nm and FWHM of 20 nm [15].…”