Two-Center Interferences in Dielectronic Transitions inH2++HeCollisions

Abstract

Molecular two-center interferences in a collision induced excitation of H2(+) projectile ions, with simultaneous ionization of helium target atoms, are investigated in a kinematically complete experiment. In the process under investigation, the helium atom is singly ionized and simultaneously the molecular hydrogen ion is dissociated. Different collision mechanisms are identified and interference fringes emerging from a correlated first-order mechanism and from an independent second-order process are observed.

Fully Differential Study of Capture with Vibrational Dissociation in p+H2 Collisions

“…The same phase shift was also reported for dissociative capture [11] and excitation [30] in H 2 + + He collisions. In both cases the phase shift was explained by a change of symmetry in the electronic state during the transition.…”

“…Nevertheless, the shift of the interference pattern was reproduced by a calculation, in which the interference term is included from first principles [14]. A comprehensive evaluation of these experimental and theoretical results suggests that the two-center interference pattern is not fully understood yet: while two data sets ( [11,30])…”

Fully differential study of dissociative single capture and Coulomb explosion through double capture in p+H2 collisions

“…An example is molecular two-center interference, which has been observed in numerous experimental studies and predicted by theory for charged particles colliding with diatomic molecules [e.g. [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. There, the diffracted projectile waves originating from the two atomic centers interfere with each other.…”

“…One approach to identify an interference pattern even when it is not or barely visible in the cross sections is to normalize the cross sections to those one would obtain without the interference term, to which we refer as the incoherent cross section dσ inc . In analogy to classical optics the cross section including the interference term I (coherent cross section) can be expressed as dσ coh = dσ inc I so that I is given by the coherent to incoherent cross section ratio R [7][8][9][10]13,15,16]. The difficulty with this approach is that until recently it was not clear how dσ inc could be experimentally determined.…”

Imaging molecular geometry with electron momentum spectroscopy

“…This oscillation phenomenon is usually referred to as bond oscillation17, which can also be regarded as a result of the Cohen-Fano type18 or the Young-type interference effect originated from the coherent superposition of the ( e , 2 e ) amplitudes from the atoms in the molecule. This type of molecular scale interference was first proposed by Cohen and Fano18 in photoionization and was successively demonstrated in the ionization of molecules induced by heavy ions19202122232425, photons26272829303132333435, as well as electrons363738.…”