GB918878A - High resolution scanning spectroscope - Google Patents

Abstract

918,878. Photo-electric high-resolution spectroscopy. IMPERIAL CHEMICAL INDUSTRIES OF AUSTRALIA & NEW ZEALAND Ltd. Dec. 19, 1960, No. 43656/60. Class 40 (3). A range of wavelengths in a beam of light, ultra-violet or infra-red radiation is scanned by passing the beam into an absorbing medium and applying either the Zeeman or Stark effect to the source of the beam or the absorbing medium. An emission spectral line in the light beam 10, Fig. 1, is investigated by putting a gas in the chamber 12 which has an absorption line near the emission line, splitting the absorption line with the Zeeman effect provided by the coils 20, removing one split component with a nicol prism 14 and a quarter-wave plate 15, varying the current in coils 20 to scan the remaining component relative to the emission line and recording the variation of output of a photomultiplier 17 on XY recorder or oscilloscope 19. In Fig. 2 (not shown), the resonant radiation is measured to indicate the absorption. Measurement of partial pressures.-Light from a lamp 40, Fig. 5, excites resonance in a chamber 43 to an extent dependent upon the concentration of the scattering atoms and this is detected by a photo-cell 45, compared with the output of a correction photo-cell 47 and recorded. To eliminate variations due to line shift and broadening the whole line is scanned and the output integrated. Measurement of temperature.-Source temperature is measured by scanning the emission line with a narrow absorption line to determine the Doppler broadening. The temperature of an absorber is determined by measuring the half-width of a line absorbed from a continuum, or by scanning the absorption line with a narrow emission line. Isotope analysis.-An isotope mixture in the source or absorber is investigated using a pure isotope in the absorber or source, respectively. The relative intensity of the emission or absorption lines due to the individual isotopes indicates the relative abundance. The isotopes investigated may be in the upper atmospherestrontium, lithium or sodium fluorescing under excitation by the sun, auroral electrons or cosmic rays. Measurement of gas velocity.-Light frdm a source 51, Fig. 6, is passed in two different directions through a wind tunnel into which has been introduced atoms of an absorbing gas. The emission line is shifted by the Zeeman effect to scan the absorption lines on the two paths and the Doppler shift therebetween indicates the wind tunnel gas velocity. The velocity of gas in the upper atmosphere is measured by scanning the fluorescence therefrom with an absorption line and determining the Doppler shift and broadening of the line. Specification 918,879 is referred to.