Effects of association of rhodamine 6G compounds on the IR absorption spectra

Results are reported for association with the anions Cl^–, Br^–, I^–, NO ₃ ^– , ClO ₄ ^– , GaCl ₄ ^– , and InBr ₄ ^– , as regards the IR absorption of free and bound N-H modes. The bound N-H mode is found to be characteristic of the anion and to be due to association of ion pairs joined via hydrogen bonds.     

Solvent effects on the gain of rhodamine 6G

The effect of solvents on the gain and the peaks of gain spectra is investigated for rhodamine 6G (R6G) under nitrogen laser pumping. The non-specific solute-solvent interaction for R6G is found to be mainly dispersive. Additional shifts produced for R6G in certain solvents are explained as due to hydrogen bonding. The gain characteristics are interpreted on the basis of the position and overlap of absorption and fluorescence spectra, the quantum yield, the absorption at the pumping wavelength and the refractive index of the solvent. For the solvents studied it is found that R6G has high gain in solvents with low refractive index and high polarity. Amongst the solvents studied the alcohols displayed the highest gain with methanol being the most suitable solvent. The lowest gain amongst the alcohols was with capryllic alcohol which gave a gain that was 69% of that obtained with methanol. Amongst all the solvents studied the lowest gain was with chloroform, being only 34% of the gain in methanol.     

Effect of cyclooctatetraene on the laser properties of rhodamine 6G solution under flashlamp excitation

The metastable level lifetime of rhodamine 6G in ethanol solution was measured by a dye laser with and without a cyclooctatetraene additive. In contrast to the existing ideas it was shown that the presence of cyclooctatetraene not only fails to decrease but on the contrary increases the lifetime τ_T of this dye. The improvement observed in the oscillation properties is expected to be connected with the decrease of the interconversion rate in a rhodamine 6G molecule when it is surrounded by a shell of the cyclooctatetraene molecules.     

On the mechanism of rhodamine 6G fluorescence quenching

The fluorescence of the widely used TPF dye rhodamine 6G is quenched by photons of the ruby as well as the Nd-glass laser. Taking into consideration the polarisation of the ground- and excited-state absorptions of rhodamine 6G a simple model of quenching results. The main process is an S₁ absorption with subsequent leave of the ordinary rhodamine 6G singlet system. For Nd-laser photons the cross section of the concerned transition following from our quenching experiments is σS₁→S₂ = 1.2×10^-16 cm².     

Theoretical study on SERRS of rhodamine 6G adsorbed on Ag2 cluster: chemical mechanism via intermolecular or intramolecular charge transfer

The problem of the chemical enhancement of rhodamine 6G (R6G) adsorbed on silver cluster has been theoretically investigated by charge difference densities (CDDs) to show the direct charge transfer (CT) evidence. For surface‐enhanced resonance Raman scattering (SERRS) of R6G excited at 514.5 nm, the enhancements of v(151) and v(154) result from weak intermolecular (from Ag to R6G) CT and the strong intramolecular CT [similar to that of resonance Raman scattering (RRS) of R6G], respectively. The possibility of the SERRS of R6G contributed from pure intermolecular CT is also discussed, when the incident light is close to the new metal–R6G CT excited state at 1571.4 nm. Meanwhile compared with the absorption process the fluorescence yield of R6G is investigated by transition densities and CCDs. Copyright © 2008 John Wiley & Sons, Ltd.     

Effect of soap on the fluorescent lifetime and quantum yield of rhodamine 6G in water

Addition of the soap ammonyx LO to a solution of 2 × 10^-4Mrhodamine 6G in water lengthens the fluorescent lifetime from 3.8 to 5 nsec, and increases the relative quantum yield by ≈ 1.5. Concentrations of soap and solute are those commonly used in cw rhodamine dye lasers. Comparisons are made with rhodamine 6G in ethanol solutions.     

Photochemical stability of rhodamine 6G in solution

The photochemical stability of Rhodamine 6G under ultraviolet and copper-vapour laser irradiation has been determined. A strong dependence of this reaction on the solvent has been found. The results indicate a free-radical mechanism as a possible reaction pathway for photobleaching.