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Title: Precision atomic beam density characterization by diode laser absorption spectroscopy

Abstract

We provide experimental and theoretical details of a simple technique to determine absolute line-of-sight integrated atomic beam densities based on resonant laser absorption. In our experiments, a thermal lithium beam is chopped on and off while the frequency of a laser crossing the beam at right angles is scanned slowly across the resonance transition. A lock-in amplifier detects the laser absorption signal at the chop frequency from which the atomic density is determined. The accuracy of our experimental method is confirmed using the related technique of wavelength modulation spectroscopy. For beams which absorb of order 1% of the incident laser light, our measurements allow the beam density to be determined to an accuracy better than 5% and with a precision of 3% on a time scale of order 1 s. Fractional absorptions of order 10{sup −5} are detectable on a one-minute time scale when we employ a double laser beam technique which limits laser intensity noise. For a lithium beam with a thickness of 9 mm, we have measured atomic densities as low as 5 × 10{sup 4} atoms cm{sup −3}. The simplicity of our technique and the details we provide should allow our method to be easily implemented inmore » most atomic or molecular beam apparatuses.« less

Authors:
;  [1]
  1. Physics Department, The College of the Holy Cross, Worcester, Massachusetts 01610 (United States)
Publication Date:
OSTI Identifier:
22597620
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 87; Journal Issue: 9; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ABSORPTION; ABSORPTION SPECTROSCOPY; ACCURACY; ATOMIC BEAMS; DENSITY; LASER SPECTROSCOPY; LASERS; LITHIUM; LOCK-IN AMPLIFIERS; MOLECULAR BEAMS; RESONANCE; SIGNALS; THICKNESS; WAVELENGTHS

Citation Formats

Oxley, Paul, and Wihbey, Joseph. Precision atomic beam density characterization by diode laser absorption spectroscopy. United States: N. p., 2016. Web. doi:10.1063/1.4962025.
Oxley, Paul, & Wihbey, Joseph. Precision atomic beam density characterization by diode laser absorption spectroscopy. United States. doi:10.1063/1.4962025.
Oxley, Paul, and Wihbey, Joseph. Thu . "Precision atomic beam density characterization by diode laser absorption spectroscopy". United States. doi:10.1063/1.4962025.
@article{osti_22597620,
title = {Precision atomic beam density characterization by diode laser absorption spectroscopy},
author = {Oxley, Paul and Wihbey, Joseph},
abstractNote = {We provide experimental and theoretical details of a simple technique to determine absolute line-of-sight integrated atomic beam densities based on resonant laser absorption. In our experiments, a thermal lithium beam is chopped on and off while the frequency of a laser crossing the beam at right angles is scanned slowly across the resonance transition. A lock-in amplifier detects the laser absorption signal at the chop frequency from which the atomic density is determined. The accuracy of our experimental method is confirmed using the related technique of wavelength modulation spectroscopy. For beams which absorb of order 1% of the incident laser light, our measurements allow the beam density to be determined to an accuracy better than 5% and with a precision of 3% on a time scale of order 1 s. Fractional absorptions of order 10{sup −5} are detectable on a one-minute time scale when we employ a double laser beam technique which limits laser intensity noise. For a lithium beam with a thickness of 9 mm, we have measured atomic densities as low as 5 × 10{sup 4} atoms cm{sup −3}. The simplicity of our technique and the details we provide should allow our method to be easily implemented in most atomic or molecular beam apparatuses.},
doi = {10.1063/1.4962025},
journal = {Review of Scientific Instruments},
number = 9,
volume = 87,
place = {United States},
year = {Thu Sep 15 00:00:00 EDT 2016},
month = {Thu Sep 15 00:00:00 EDT 2016}
}
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  • A direct measurement of atomic flux in {ital e}-beam evaporated yttrium has been demonstrated with a diode-laser-based atomic absorption (AA) monitor at 668 nm. Atomic number density and velocity were measured through absorption and Doppler shift measurements to provide the atomic flux. The AA-based deposition rates were compared with independent quartz crystal monitors showing agreement between the two methods. {copyright} {ital 1997 American Institute of Physics.}
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