Ionisation energies and electronic structures of the phenyl 1,3-dipoles

The He(I) photoelectron spectra of phenyldiazomethane (molecule 1), phenyl azide (molecule 2), benzonitrile-N-oxide (molecule 3) and C-phenyl N-methyl-     

Efficient stimulated Raman scattering in silicon

Stimulated Raman scattering in silicon was investigated at liquid helium temperatures. A Q-switched single mode Nd: YAG laser was used to generate Stokes radiation at 1.127 μm. Time resolved measurements give a maximum power conversion efficiency of 20%. The effects of intensity induced losses are discussed.     

Magnetic order induced birefringence and critical behaviour of the long range order parameter in NiO

The optical linear magnetic birefringence of single-domain NiO crystals was measured at temperatures above and below the antiferromagnetic phase transition. The analysis of the experimental data yield a Néel temperature of T_N = (523.7 ± 0.2)K and a critical exponent β = 0.325^+0.01_-0.02 which determines the temperature behaviour of the magnetic long range order parameter $\text{S}\text{?}\text{～ (}\text{1?T}\text{T}{}_{\mathrm{N}}\text{)}{}^{\mathrm{\beta }}$. This critical behaviour of S? is found to be continued to temperatures well below T_N.     

Fluorescence quantum yields and cascade-free lifetimes of state selected CO+2, COS+, CS+2 and N2O+ determined by photoelectron—photon coincidence spectroscopy

The details and principles of an apparatus built for measurements of fluorescence quantum yields and cascade-free lifetimes of open-shell cations are reported. These rely on the detection of coincidences between energy selected photoelectrons and undispersed photons. The results of such measurements for CO⁺₂, COS⁺, CS⁺₂ and N₂O⁺ in selected vibrational levels of their excited states are presented. Non-unity fluorescence quantum yields are found for some vibronic levels of CO⁺₂($\text{B}$), COS⁺ ($\text{A}$), N₂OP⁺($\text{A}$) and a non-exponential decay is observed for CS⁺₂($\text{A}$). The data yield the following values for the radiative lifetimes: CO⁺₂($\text{A}$) 124 ± 6 ns, CO⁺₂($\text{B}$) 140 ± 7 ns, COS⁺($\text{A}$) 550 ± 50 ns and N₂O⁺($\text{A}$) 240 ± 12 ns.     

Emission spectra of the cations of some fluoro-substituted phenols in the gaseous phase

Emission spectra of the cations of 2,5- and 3,5-difluorophenol, of 2,3,4- and 2,4,5-trifluorophenol, of 2,3,5,6-tetrafluorophenol and of 2,3,4,5,6-pentafluorophenol have been obtained in the gas phase using low-energy electron beam excitation. The band systems are assigned to the B?(π^?1) → X?(π^?1) electronic transitions of these cations by reference to photoelectron spectroscopic data. The He(Iα) photoelectron spectra and the ionisation energies of ten fluoro-substituted phenols are reported. The symmetries of the four lowest electronic states of these cations are inferred from the radiative decay studies. The lifetimes of the lowest vibrational levels of the B?(π^?1) state of the six fluoro-substituted phenol cations above have also been measured.