TY - JOUR
T1 - Two roads converged in a yellow dye
T2 - Unusual spectral broadening in the emission of Auramine-O possibly caused by low-friction intramolecular rotation
AU - Erez, Yuval
AU - Simkovitch, Ron
AU - Akulov, Katherine
AU - Gepshtein, Rinat
AU - Schwartz, Tal
AU - Huppert, Dan
N1 - Publisher Copyright:
© 2014 American Chemical Society.
PY - 2014/11/20
Y1 - 2014/11/20
N2 - Steady-state and time-resolved optical techniques were employed to study the rather complex relaxation of excited states of Auramine-O (AuO) in several liquids at room temperature. We found three relaxation times in the decay of the pump-probe signals of the excited states of AuO. We focused our study on the short time decay, with a duration of within about 150-300 fs. We found that the temporal changes of the emission band of AuO could be divided into three behaviors, depending on the solvent characteristics. In dimethyl sulfoxide (DMSO), a hydrogen-bond-accepting solvent, AuO, shows, at short times, a relatively broad emission band with small changes in its peak position and width as a function of time. In acetonitrile and in acetic acid, both hydrogen-bond-donating solvents, we found large changes in the band peak and width as a function of time. Dichloromethane is a solvent lacking strong solvent interactions, it is apolar and is neither a strong hydrogen-bond-donator nor a strong hydrogen-bond-acceptor. For AuO in dichloromethane we found an oscillation with a time constant of 200 fs in the time-resolved emission signal. We attribute the rather large changes of the emission band with time in the short time window to the twist of the dimethylamino groups of the aniline groups of AuO. (Graph Presented).
AB - Steady-state and time-resolved optical techniques were employed to study the rather complex relaxation of excited states of Auramine-O (AuO) in several liquids at room temperature. We found three relaxation times in the decay of the pump-probe signals of the excited states of AuO. We focused our study on the short time decay, with a duration of within about 150-300 fs. We found that the temporal changes of the emission band of AuO could be divided into three behaviors, depending on the solvent characteristics. In dimethyl sulfoxide (DMSO), a hydrogen-bond-accepting solvent, AuO, shows, at short times, a relatively broad emission band with small changes in its peak position and width as a function of time. In acetonitrile and in acetic acid, both hydrogen-bond-donating solvents, we found large changes in the band peak and width as a function of time. Dichloromethane is a solvent lacking strong solvent interactions, it is apolar and is neither a strong hydrogen-bond-donator nor a strong hydrogen-bond-acceptor. For AuO in dichloromethane we found an oscillation with a time constant of 200 fs in the time-resolved emission signal. We attribute the rather large changes of the emission band with time in the short time window to the twist of the dimethylamino groups of the aniline groups of AuO. (Graph Presented).
UR - http://www.scopus.com/inward/record.url?scp=84914689091&partnerID=8YFLogxK
U2 - 10.1021/jp5070903
DO - 10.1021/jp5070903
M3 - ???researchoutput.researchoutputtypes.contributiontojournal.article???
AN - SCOPUS:84914689091
SN - 1932-7447
VL - 118
SP - 27063
EP - 27073
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 46
ER -