Photo-induced intramolecular electron transfer and intramolecular vibrational relaxation of rhodamine 6G in DMSO revealed by multiplex transient grating spectroscopy

Abstract

Photo-induced intramolecular electron transfer (PIET) and intramolecular vibrational relaxation (IVR) dynamics of the excited state of rhodamine 6G (Rh6G + ) in DMSO are investigated by multiplex transient grating. Two major components are resolved in the dynamics of Rh6G + . The first component, with a lifetime τ PIET = 140 fs-260 fs, is attributed to PIET from the phenyl ring to the xanthene plane. The IVR process occurring in the range τ IVR = 3.3 ps-5.2 ps is much slower than the first component. The PIET and IVR processes occurring in the excited state of Rh6G + are quantitatively determined, and a better understanding of the relationship between these processes is obtained.

A combined theoretical and experimental study of the ultrafast photophysics of Rhodamine B

“…The longer timescale observed here may be related to the higher polarity of the solvent. Similar timescales were also observed in the transient grating spectra of Rh6G in DMSO (3.3 -3.9 ps) [43] and transient absorption in Rh101 in methanol (3.15 and 15.2 ps) [41]. Although various dynamics have been assigned to this timescale we agree with the prevailing assignments to ultrafast solvent rearrangement in response to the new electronic distribution immediately following the photoexcitation of the molecule.…”

“…In previous works on Rh6G this short timescale has been observed but was assigned exclusively to ultrafast photoinduced electron transfer [42]. has also been reported in the Rhodamine literature for a range of ultrafast optical experiments from transient gratings to transient absorptions [19,41,43]. A slightly shorter timescale of 1.4 ps was observed in the transient absorption spectra of RhB in MeCN and extracted through a global analysis and assigned to a narrow spectral feature [19].…”

Transient grating study of the intermolecular dynamics of liquid nitrobenzene

“…In the past decades, TG technique has been widely used to study inter-or intra-molecular energy transfer and laser-induced ultrasonic waves, etc. [15][16][17] In the present work, we will demonstrate that when the sample is non-resonantly excited by the grating writing pulses, the transient Kerr grating caused by laser-induced birefringence can also provide a wealth of information about intermolecular dynamics of liquid. Using nitrobenzene as the sample, three exponential relaxation processes can be observed in the dynamic curve, which shows that the TG technique is very sensitive to molecular motion in liquid.…”