Excess photon detachment of H{sup {minus}} ions with 1.17 eV photons
- and others
One- and two-photon detachment of electrons from the negative hydrogen ion are observed with 1.17 eV laser pulses from a Nd:YAG laser. To the authors knowledge, the 2-photon detachment is the first experimental observation of non-resonant excess photon detachment (EPD) from the negative hydrogen ion. This apparatus was previously used to perform the first resonant multiphoton detachment of the {sup 1}D{sup e} resonance of H{sup {minus}} just below the n=2 threshold. A Penning ion source produces an 8{mu}A, 35 keV H{sup {minus}} beam in 500 ns pulses at a 5 Hz repetition rate. The laser beam consists of pulse energies of up to 1 J cylindrically focused down to a 13 {mu}m waist in the ion beam direction, creating an interaction region with laser intensities of up to 10{sup 11} W/cm{sup 2}. The resulting photoelectrons are detected by a microchannel plate (MCP) at the end of a 1 m time-of-flight drift tube. The outer electron of H{sup {minus}} has a binding energy of 0.75 eV, thus one 1.17 eV photon provides an excess energy of 0.42 eV. By rotating the linear polarization angle the authors studied the angular distribution of the electrons for both 1 - and 2-photon detachments. The spectra were compared to a model based on a Legendre polynomial expansion of the time differential photo-ionization cross section. Studies of the peak size vs the laser intensity were also performed.
- OSTI ID:
- 394186
- Report Number(s):
- CONF-9605105--
- Journal Information:
- Bulletin of the American Physical Society, Journal Name: Bulletin of the American Physical Society Journal Issue: 3 Vol. 41; ISSN BAPSA6; ISSN 0003-0503
- Country of Publication:
- United States
- Language:
- English
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