Photoionization of water molecules by attopulses assisted by near-infrared lasers

FOJÓN, OMAR A.; BOLL, DIEGO I.R.; MARTINI, LARA

Moscú

Congreso; The International Conference on Many Particle Spectroscopy of Atoms, Molecules, Clusters and Surfaces MPS; 2016

ABSTRACTSince organic matter is composed mostly of water, the reactions involving this molecule are essential to understand the interaction betweenradiation and the biological tissue. In this work, we study theoretically the photoionization of water molecules by extreme ultraviolet (XUV) attopulses assisted by lasers in the near-infrared (NIR) range.Firstly, we obtain monochromatic cross sections in the framework of the dipole approximation within the velocity gauge. We use a simple model where the final state wavefunction is given by a Coulomb continuum wavefunction and the water molecule. We employ several representations for the H 2 O molecule orbitals. We compute multiple differential cross sections for fixedin-space molecules analysing the orientation effects. We compare our predictions with more elaborated theoretical results and experimental results obtained by other authors. A reasonable agreement is obtained with the available experimental data especially at high enoughenergies where there is a lack of elaborated results due to their high computational cost.Secondly, we consider the photoionization reaction by XUV attopulses assisted by NIR lasers. We analyse photoelectron angular distributions(AD) for different delays between the attopulse and the assistant laser field. We compare our results for water and Ne atoms as they belongto the same isoelectronic series. Moreover, we contrast our calculations with previous theoretical and experimental work for Ar atoms dueto the similarities of the orbitals involved in the reaction. To this end, we use a model in which the temporal evolution of the system can be divided into three stages that allows spatial and temporal separation for the Coulomb and Volkov final state wavefunction. The observables are calculated in the framework of a nonrelativistic and non-perturbative approximation. It is expected that these studies promote progress on the control of the chemical reactivity of water molecules and help to understand the energy deposition in the irradiation of living matter during very short time intervals.