The S1−S0 transitions of 1,2,3-trimethylbenzene and 3-fluoro-1,2-dimethylbenzene observed by two-photon spectroscopy

Two-photon (TP)-induced transitions to the ¹L_b state of 1,2,3-trimethylbenzene and 3-fluoro-1,2-dimethylbenzene were studied by resonant multiphoton ionization in a supersonic jet beam. In both molecules the TP S₁ ← S₀ transition has very strong Franck-Condon components and components vibronically induced by ν₁₄. Seven fundamental vibrations of the ¹L_b state are detected in each molecule. A band, which appears near 14₀¹ due to a Fermi resonance, is proposed to be 1₀²15₀¹. The ¹L_b intensity of the heterosubstituted compound is in agreement with the TP orientation intensity rules.     

Structure determination of sec-butylbenzene rotamers by UV spectroscopy and ab initio calculations

Sec-butylbenzene has been investigated using resonant two-photon ionization (R2PI) and UV–UV hole-burning spectroscopy aided by ab initio calculations. All three conformers predicted from theory are observed in the spectrum, and are assigned by rotational band contour analysis. The most strongly populated conformer (G1) has a gauche arrangement of the side chain dihedral angle τ₂(C₁C_αC_βC_γ). The populations of the anti (A) and the remaining gauche conformer (G2) are about 7% and 2%, respectively. The alpha methyl group is found to significantly affect the conformational preferences in sec-butylbenzene (sec-BB), compared to n-propylbenzene in which the anti conformer is favored.     

Detection of the ππ* E2g state in sym-tetrafluorobenzene

The VUV absorption spectrum of gaseous 2,3,5,6-tetrafluorobenzene is reported up to its first IP. The absolute extinction coefficient and f value are given. A band appearing at 6.85 eV is attributed to the E_2g benzene parent state with f = 0.06. A similar band is found in 1,3,5-trifluorobenzene, where the E_2g ← A_1g transition is symmetry allowed.     

A two-sided Arnoldi algorithm with stopping criterion and MIMO selection procedure

In this paper we introduce a two-sided Arnoldi method for the reduction of high order linear systems and we propose useful extensions, first of all a stopping criterion to find a suitable order for the reduced model and secondly, a selection procedure to significantly improve the performance in the multi-input multi-output (MIMO) case. One application is in micro-electro-mechanical systems (MEMS). We consider a thermo-electric micro thruster model, and a comparison between the commonly used Arnoldi algorithm and the two-sided Arnoldi is performed.     

The extinction coefficient of benzene vapor in the region 4.6 to 36 eV

Extinction coefficient spectra and oscillator strength values for the benzene transitions in the 4.6 to 9.2 eV region have been measured taking into account the effect of the instrumental bandwidth. By normalizing Koch and Otto's (1) uncalibrated absorption spectrum at 6 to 36 eV with our spectrum recorded with the same bandpass we provide values of ? in the region 4.6 to 36 eV. The dependence of ?_max on the bandpass is presented and a comparison is made between theoretical band intensities in a progression and band intensities measured experimentally. A total integrated intensity of 0.075 is found for the Rydberg transitions below the first I.P. and a total value of 17.5 is found for the whole region 4.6 to 36 eV.     

Working group report: Heavy-ion physics and quark-gluon plasma

This is the report of Heavy Ion Physics and Quark-Gluon Plasma at WHEPP-09 which was part of Working Group-4. Discussion and work on some aspects of quark-gluon plasma believed to have created in heavy-ion collisions and in early Universe are reported.