アルファ粒子の衝突, 及び重陽子の衝突による重陽子の分解

京都大学0048新制・課程博士理学博士理博第142号新制||理||97(附属図書館)2266京都大学大学院理学研究科物理学第二専攻(主査)教授 柳父 琢治, 教授 小林 稔, 教授 武藤 二郎学位規則第5条第1項該当Kyoto UniversityDA

Resonant Neutral-Particle Emission in Collisions of Electrons with Peptide Ions in a Storage Ring

Electron-biomolecular ion collisions were studied using an electrostatic storage ring with a merging beam technique for singly protonated peptides (angiotensin I, II and III). A strong neutral-particle emission at around 6.5 eV was found in addition to neutrals from recombination at low energies. The rates of the high-energy peak greatly decreased with a slight decrease in the number of amino-acid residues from angiotensin I to III. These results suggest that some peptide bonds were selectively cleaved

Resonant neutral-particle emission after collisions of electrons with base-stacked oligonucleotide cations in a storage ring

Electron-cation collisions have been studied for various protonated deoxyoligonucleotide monocations, using an electrostatic storage ring equipped with a merged-electron-beam device. Resonant neutral-particle emissions have been observed at a collision energy of about 4.5 eV for some of them. The resonance parameters depend on DNA base composition and sequence, and the resonances occur only in oligonucleotide monocations with base stacking. The resonance widths increase with oligonucleotide length, but saturate at trimers. Quantum-chemical estimations performed here help explain these results

Regular Threshold-Energy Increase with Charge for Neutral-Particle Emission in Collisions of Electrons with Oligonucleotide Anions

Electron-DNA anion collisions were studied using an electrostatic storage ring with a merging electron-beam technique. The rate of neutral particles emitted in collisions started to increase from definite threshold energies, which increased regularly with ion charges in steps of about 10 eV. These threshold energies were almost independent of the length and sequence of DNA, but depended strongly on the ion charges. Neutral particles came from breaks of DNAs, rather than electron detachment. The step of the threshold energy increase approximately agreed with the plasmon excitation energy. It is deduced that plasmon excitation is closely related to the reaction mechanism

Relaxation of green fluorescent protein chromophore anion observed by photodissociation in an electrostatic storage ring

The gas-phase absorption properties of the green fluorescent protein chromophore anion were studied using an electrostatic storage ring. The time sequence of neutral particles produced by photodissociation was detected following laser irradiation. The lifetimes of the photo-absorbed ions depended on their storage time in an ion trap before injection into the storage ring. The lifetime increasedwith the storage time and saturated, indicating a change in the population of rovibrationally excited states with respect to the storage time. Photodissociation neutral spectrum of the relaxed ions measured as a function of the laser wavelength was characterized by a narrow asymmetric shape, which was in good agreement with the photo fragment ion action spectrum reported recently