Isomer-specific photofragmentation of CH at the carbon K-edge.

Individual fingerprints of different isomers of CH cations have been identified by studying photoionization, photoexcitation, and photofragmentation of CH near the carbon K-edge. The experiment was performed employing the photon-ion merged-beams technique at the photon-ion spectrometer at PETRA III (PIPE). This technique is a variant of near-edge X-ray absorption fine-structure spectroscopy, which is particularly sensitive to the 1s → π* excitation.

X-Ray absorption spectroscopy of HO.

We report the X-ray absorption of isolated HO cations at the O 1s edge. The molecular ions were prepared in a flowing afterglow ion source which was designed for the production of small water clusters, protonated water clusters, and hydrated ions. Isolated HO cations have been analyzed for comparison.

Double differential cross sections for proton induced electron emission from molecular analogues of DNA constituents for energies in the Bragg peak region.

For track structure simulations in the Bragg peak region, measured electron emission cross sections of DNA constituents are required as input for developing parameterized model functions representing the scattering probabilities. In the present work, double differential cross sections were measured for the electron emission from vapor-phase pyrimidine, tetrahydrofuran, and trimethyl phosphate that are structural analogues to the base, the sugar, and the phosphate residue of the DNA, respectively. The range of proton energies was from 75 keV to 135 keV, the angles ranged from 15° to 135°, and the electron energies were measured from 10 eV to 200 eV.