Photodetachment spectroscopy from cooled negative ions. Summer research in the AMO lab* June August 2005. James Wells. * Support from Davidson College and the American Chemical Society. -. -. -. -. -. +. +. -. -. -. -. Photodetachment. -. X - + photon X + e - - PowerPoint PPT Presentation
Photodetachment spectroscopy from cooled negative ionsJames Wells
Summer research in the AMO lab*June August 2005* Support from Davidson College and the American Chemical Society
Photodetachment- X- + photon X + e-
Equivalent to latter half of an electron-atom collision.
Effects of ions random motionPhoton frequency is Doppler broadenedCauses uncertainty E in any energy-dependent measurementTypical experimental goal: measure probability of detachment as f(Ephoton)E blurs experimental results: fewer details, less contrast/structure.
Ions trapped in an ion trap: electrostatic potential well.
Ion trap apparatus
Ring dye laser
Laser LabVIEW control code(Screen shot)
Negative Ion Formation
Short-range attractive potential (~ 2 eV deep and a few wide)
Electron correlation effects partly responsible for covalent bonds
Energy Levels (Oxygen)
Photodetachment with B-Fields departing electron executes cyclotron motion in field
motion in plane perpendicular to B is quantized to cyclotron levels
cyclotron states separated by = eB/me
motion along axis of field is continuous, non-quantized
for typical B = 1.0 Tesla, 30 GHz, period = 36 ps
quantized Landau levels add structure to detachment cross section
Detachment cross section in B field
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