B.R. Russell

Population and rotational kinetics of the rhodamine B monomer and dimer: Picosecond transient spectrometry

We use picosecond excite‐and‐probe techniques at 532 nm, a subnanosecond fluorescence spectrometer, and a transient‐transmission spectrometer with picosecond temporal resolution to measure the population kinetics and rotational diffusion of aqueous rhodamine B monomer and dimer. The excited‐state lifetimes of the monomer and dimer are determined to be 1.6 ns and 100 ps, respectively, and the rotational randomization time of the monomer is measured to be 250 ps. The dimer rotational diffusion time is determined to be longer than that of the monomer, indicating that there is a large molecular species in equilibrium with the monomer.

Electric dichroism spectroscopy in the vacuum ultraviolet dimethylsulfide and thiiran

Abstract Electric field techniques have been used to investigate certain s, p and d Rydberg absorption bands for dimethylsulfide (DMS) and ethylene sulfide (thiirane) with respect to the polarization of the transitions, the dipole moment, and mean polarizability changes that occur upon excitation.

The vacuum ultraviolet spectra of three transition metal hexacarbonyls

Abstract Reported are the vapor phase spectra of Cr(CO)6, Mo(CO)6, W(CO)6, at 300°K in the vacuum ultra-violet region 2200 - 1250 A. Several new transitions are seen with preliminary interpretations in terms of a simple bond-excition model and compared with some recent photoionization studies.

The vacuum ultraviolet spectra of methylvinylsilane and propylene

Abstract The VUV spectra of methylvinylsilane and propylene are reported and corresponding transitions are assigned. The small red shift of the π→π* transition and the large blue shift of the σ→σ* excitation of the methyl group in methylvinylsilane may be attributed to the +I inductive effect of silicon without involving interaction between d orbitals and the π system. No evidence for a second allowed π→π transition is found in methylvinylsilane.

Level decay and orientational kinetics of the rhodamine B monomer and dimer

Abstract The population kinetics and the rotational diffusion of the rhodamine B monomer and dimer were measured by using picosecond pulses from a mode-locked Nd : YAG laser to induce and time resolve the concentration-dependent transient absorption saturation of various aqueous solutions of this organic dye.

The vacuum ultraviolet spectra of fluorine chlorine substituted trivalent phosphorus

Abstract The vapor phase absorption spectra of PF3, PF2Cl, PFCl2, and PCl3 are reported in the vacuum ultraviolet spectral region 2400—1200 A. These results are compared with information obtained from photoelectron spectra. A brief discussion of the spectra in terms of analogous absorption regions and results from CNDO/2 calculations are given.

The vacuum ultraviolet absorption spectrum of 1,1-dichloro-2,2-difluoroethylene

Abstract The vacuum ultraviolet absorption spectrum of 1,1-dichloro-2,2-difluoroethylene is reported. Two Rydberg progressions converging on an ionization potential of 9.69 ± 0.01 eV are described. The π* ← π (V ← N) transition energy (57471 cm −1 ) and ionization potential are discussed in terms of data for similar compounds.

The vacuum ultraviolet spectrum of bromosilane

Abstract The vacuum ultraviolet absorption spectrum of bromisilane in the vapor phase is reported. Assignments are made using photoelectron data and oscillator strengths. The absorptions of this compound are related to absorptions of chlorosilane, methyl bromide and methyl chloride. The results of this work indicate the presence of dπ-pπ (Siue5f8Br) delocalizations and concomitant stabilization of halogen nonbonding electrons.

Changes in excited-state dipole moments with variations in pressure of the gaseous dielectric SF6

Abstract Electrochromism data are presented for the π* ← π transition of aniline and the 3s ← n transitions of acetone and cyclopentanone when the pressure of the arc-suppressor gas (SF 6 ) is increased. Second dielectric virial coefficients for these excited states are estimated from the variations in the dipole-moment changes.

Electric Field Studies in the Vacuum Ultraviolet

The application of intense electric fields induces a partial orientation of gaseous polar compounds. This orientation effect causes certain changes in the absorption band profile, changes which have been used to determine a number of excited-state parameters for several series of compounds [1–5]. These parameters include properties such as the change in dipole moment, change in polarizability and polarization of the transition moment. In gen eral, the emphasis of these studies has been on characterizing ab sorption bands which occur in the lower-energy portion (200 to 170 nm) of the vacuum ultraviolet (VUV) spectral region. Many electronic transitions which occur in this spectral region have conflicting assignments as both intravalence and Rydberg. Excited-state properties obtained with the aid of electric field effects, however, can be used in the characterization of these absorptions and the clarification of their assignments.