Research Facility / End Station

End Stations for Gas Phase Studies
Multiplex Coincidence Apparatus for Chemical Dynamics and Spectroscopy

Contact : Kaidee Lee, ext. 7313, lee@nsrrc.org.tw

Research areas

Gas phase photofragmentation dynamics, photoionization, Auger and Coster-Kronig decay

Research interests

Energetics and decay paths of multiply ionized and highly excited molecules and intricate details of their dissociation dynamics and potential energy surfaces, with an eye to their potential application in controlled reactions driven by designer laser pulses.Selective bond breakage with core-electron excitation Dynamics of photoionization, and Auger and Coster-Kronig electron emission, as probed by anisotropy of ejected electrons.

Measuring techniques

Electron-ion coincidence with ion imaging, electron-electron coincidence, XPS, AES, XANES, ZEKE electron spectroscopy.

Capabilities

Momentum coincidence between fragment ions aimed at revelation of the minutiae of dissociation dynamics and the topography of the potential energy surfaces.

Rotation of the whole apparatus with respect to the light axis without breaking vacuum; facility for magic angle, pseudo-magic angle, pan-magic angle, and anisotropy measurements.

Ion optics capable of high mass and momentum resolution, and 4π steradian collection of ions up to 20 eV intrinsic kinetic energy, under low extraction fields suitable for coincidence measurement.

A picture of the core section of the endstation
A 3-D drawing of the full endstation

Equipment list

Hemispherical energy analyzer (PHI, OmniV lens, 16 channel detector) Time-of-flight spectrometer (1 meter, real-time 2D position-sensitive detector)

ZEKE electron detector

  • CAMAC modules:TDC, G&D generator, discriminator/latch, counter, D/A converter, timing pulse generator, crate controller, PC interface card
  • NIM modules:TAC, differential amplifier, constant fraction discriminator, linear/logic fanout, discriminator, level translator, counter/timer, ratemeter, V/F converter
  • Personal computers, power supplies, digitizing oscilloscope (Tektronix TDS 744A)
  • Pumps :Magnetically levitated turbomolecular pumps, scroll pumps, rotary vane pump