No abstract

Intense vacuum ultraviolet laser radiation is generated from rare gas excimer lasers. 9.8 eV photons from an argon excimer laser change surfaces of SiO2 to silicon. The reaction proceeds without the aid of reactive gas or solution and is thus called the “superdry process”. 9.8 eV photons create excitons via an efficient one-photon absorption process, and then these high-density excitons induce bond-breaking between Si and O.

We report on the electron spin resonance (ESR) study of the photo-oxidative stress-mediated protein conformation changes in the spin-labelled protein staphylococcal nuclease (SNase). The photo-oxidative stress was brought on by photosensitization of singlet oxygen ( 1 g ) in the presence of a novel photosensitizer, water-soluble fullerol C 60 (OH) 19 (ONa) 17 , and resulted in partial protein denaturation. This process was monitored via ESR measurements performed for a spin-labelled SNase Thr-62-Cys mutant, with MTSSL spin label (SL) attached to the cysteine 62 residue (SNase T62C-SL). Prior to ESR measurements of the oxidative stress-induced alterations in protein conformations, the efficiency of C 60 (OH) 19 (ONa) 17 for 1 g -generation was confirmed by three different techniques: (i) selective reactive scavenging of 0953-8984/07/285201+13$30.00

We develop a simple approach based on time-independent perturbation theory that leads to a frequency operator for quantum mechanical models. This method is suitable for the calculation of time-dependent physical properties free from secular terms. In particular we obtain the first-order perturbation correction to the frequency operator for a class of anharmonic oscillators.

We propose and demonstrate the use of a photostimulable phosphor material, BaFBr:Eu2+, for recording two-dimensional intensity distributions within output beams of vacuum ultraviolet lasers. The sensitivity characteristics were measured not only for nanosecond pulsed radiation from KrF, ArF, and Ar2 excimer lasers but also for quasi-continuous-wave synchrotron radiation. We designed and constructed a laser beam profiler to record, read, and erase images in vacuum. The intensity distribution in the output beams from an Ar2 excimer laser was measured with it, and then the threshold gas pressure for obtaining the well collimated beams was found to be 22 kg/cm2. The intensity is not uniform in the beams but stronger in the peripheral part than in the central one.