A crossed molecular beam apparatus using high-resolution ion imaging

Abstract

A new crossed molecular beam apparatus with a high-resolution ion imaging detector is described. Two pulsed supersonic molecular beams are crossed at right angles in a vacuum of 10−7 Torr. The collision region is irradiated with a tunable laser pulse that ionizes the scattered particles state selectively. The generated ions are accelerated by stacked electrodes in a two-dimensional (2D) space focusing mode that increases the velocity resolution of the apparatus. A cylindrical hexapole deflector is placed in the middle of the time-of-flight mass spectrometer to compensate the center-of-mass velocity of the ions and to direct them to the center of the 2D imaging detector. Real-time image processing of the charge coupled device camera signal eliminates blurring of the image detector. The performance of the apparatus was examined by observing the inelastic scattering of NO+Ar at a collision energy of 66 meV. The observed multiple rainbow peaks clearly demonstrate the high performance of the apparatus.

A Crossed Molecular Beam Imaging Study of the O(1D2)+HCl→OH+Cl(2PJ=3/2, 1/2) Reaction

“…The details of the setup were described previously [32] except for the OA C H T U N G T R E N N U N G ( P À g , the Schumann-Runge band). A precursor gas of 1 % O 2 diluted in He was expanded into the vacuum from the Even-Lavie-type pulsed valve.…”

Photodissociation of NO2 in the (2)B22 state: A slice imaging study and reinterpretation of previous results

“…This molecular beam was doubly skimmed 50 mm and 600 mm downstream from the orifice, using 1 mm and 2 mm diameter skimmers (Beam Dynamics) respectively, in order to limit its translational velocity perpendicular to the direction of travel. The second skimmer lies at the base of a set of VMI ion/electron optics based on the designs of Wrede 43 and Suzuki 44 . The electron optics were mounted so as to project the photoion or photoelectron distributions along the axis of the molecular beam propagation and were designed to operate both in conventional VMI 45 and DC slicing modes 42 depending on the extraction voltages employed.…”

Differential cross sections for collisions of hexapole state-selected NO with He

“…The velocity-mapped ion-imaging technique is now commonly used in the field of molecular dynamics. [7][8][9][10][11][12][13][14][15] Differential cross sections for inelastic collisions can also be measured using a movable detector, 16 but this technique is more time consuming and experimentally difficult. The resolution depends on the scattering angle and only the scattering angle of the molecule in the laboratory frame can be obtained.…”