A photoelectron-photoion coincidence imaging apparatus for femtosecond time-resolved molecular dynamics with electron time-of-flight resolution of {sigma}=18 ps and energy resolution {delta}E/E=3.5%

Journal Article · Sun Jun 15 00:00:00 EDT 2008 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.2949142· OSTI ID:21123941

Vredenborg, Arno; Roeterdink, Wim G; Janssen, Maurice H. M. ^[1]

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1. Laser Centre and Department of Chemistry, Vrije Universiteit, de Boelelaan 1083, 1081 HV Amsterdam (Netherlands)

We report on the construction and performance of a novel photoelectron-photoion coincidence machine in our laboratory in Amsterdam to measure the full three-dimensional momentum distribution of correlated electrons and ions in femtosecond time-resolved molecular beam experiments. We implemented sets of open electron and ion lenses to time stretch and velocity map the charged particles. Time switched voltages are operated on the particle lenses to enable optimal electric field strengths for velocity map focusing conditions of electrons and ions separately. The position and time sensitive detectors employ microchannel plates (MCPs) in front of delay line detectors. A special effort was made to obtain the time-of-flight (TOF) of the electrons at high temporal resolution using small pore (5 {mu}m) MCPs and implementing fast timing electronics. We measured the TOF distribution of the electrons under our typical coincidence field strengths with a temporal resolution down to {sigma}=18 ps. We observed that our electron coincidence detector has a timing resolution better than {sigma}=16 ps, which is mainly determined by the residual transit time spread of the MCPs. The typical electron energy resolution appears to be nearly laser bandwidth limited with a relative resolution of {delta}E{sub FWHM}/E=3.5% for electrons with kinetic energy near 2 eV. The mass resolution of the ion detector for ions measured in coincidence with electrons is about {delta}m{sub FWHM}/m=1/4150. The velocity map focusing of our extended source volume of particles, due to the overlap of the molecular beam with the laser beams, results in a parent ion spot on our detector focused down to {sigma}=115 {mu}m.

• OSTI ID: 21123941
• Journal Information: Review of Scientific Instruments, Vol. 79, Issue 6; Other Information: DOI: 10.1063/1.2949142; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
• Country of Publication: United States
• Language: English

Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
ELECTRON CORRELATION
ELECTRONS
ENERGY RESOLUTION
IONS
MASS RESOLUTION
MICROCHANNEL ELECTRON MULTIPLIERS
MOLECULAR BEAMS
MOLECULAR DYNAMICS METHOD
PHOTOELECTRON SPECTROSCOPY
PHOTON-ATOM COLLISIONS
PHOTON-MOLECULE COLLISIONS
TIME RESOLUTION
TIME-OF-FLIGHT METHOD