Ultrahigh-resolution laser spectroscopy of the S1 1B2← S0 1A transition of perylene

Abstract

a b s t r a c tA rotationally resolved ultrahigh-resolution fluorescence excitation spectrum of the S 1 S 0 transition of perylene has been observed using a collimated supersonic jet technique in conjunction with a single-mode UV laser. We assigned 1568 rotational lines of the 0 0 0 band, and accurately determined the rotational constants. The obtained value of inertial defect was positive, accordingly, the perylene molecule is considered to be planar with D 2h symmetry. We determined the geometrical structure in the S 0 state by ab initio theoretical calculation at the RHF/6-311+G(d,p) level, which yielded rotational constant values approximately identical to those obtained experimentally. Zeeman broadening of each rotational line with the external magnetic field was negligibly small, and the mixing with the triplet state was shown to be very small. This evidence indicates that intersystem crossing (ISC) in the S 1 1 B 2u state is very slow. The rate of internal conversion (IC) is also inferred to be small because the fluorescence quantum yield is high. The rotational constants of the S 1 1 B 2u state were very similar to those of the S 0 1 A g state. The slow internal conversion (IC) at the S 1 zero-vibrational level is attributed to a small structural change upon electronic transition.

Franck-Condon factors perturbed by damped harmonic oscillators: Solvent enhanced X 1Ag ↔ A1B1u absorption and fluorescence spectra of perylene

“…By performing frequency calculations at equilibrium geometries of S 0 and S 1 states, we found 16 total symmetry a g normal-mode frequencies out of 90 vibrational normalmode frequencies and the present calculation agrees well with the experimental results. 51,57 The distributions of corresponding 16 Huang-Rhys factors are shown in Table I. We have carried out the frequency calculations with equilibrium geometries of S 0 and S 1 states calculated with PCM condition, and we found that the 16 I.…”

“…The lowest singlet excited state S 1 of perylene molecule has transition type of π → π * through experimental absorption and fluorescence spectra both in gaseous phase [51][52][53] and in benzene solution. 45 Computational studies on equilibrium geometries and vibrational frequencies for ground-and the first-excited states of perylene and its electronic spectra have been performed.…”

“…This agrees well with the experimental results 51 and the previous calculation results. 44,51,56 Figure 1 shows the optimized geometries with (TD) B3LYP/6-31G(d) method in gas phase in which the bond lengths and angles in the S 0 and S 1 states are very similar. The bonds C3-C4 and C5-C6 are stretched by 0.02 Å and 0.03 Å, respectively, from S 0 to S 1 state; while the bond C4-C5 is shortened from 1.406 Å to 1.388 Å and the bond C6-C29 from 1.476 Å to 1.444 Å.…”

Laboratory Spectroscopy of PAHs

“…precision (Kowaka et al 2010). This latter study shows the very small geometry change between the ground and excited states of perylene, to which its high fluorescence yield is attributed.…”

Electronic Spectroscopy of PAHs

“…Although the spectra were somehow all known, the unprecedented spectral resolution opened the possibility of a complete analysis, from spectral linewidths to rotational constants and detailed geometries. Azulene, naphthalene, pyrene and perylene, as well as benzene, have all been measured Yoshida et al 2009;Baba et al 2009b;Semba et al 2009;Kowaka et al 2010). In addition, application of a magnetic field in the lasermolecules interaction zone was performed in order to probe the Zeeman effect.…”