INFRARED ABSORPTION SPECTRA OF ISOTOPICALLY-ENRICHED LITHIUM HYDRIDE

Journal Article · Fri Jun 01 04:00:00 EDT 1962 · Dissertation Abstr.

OSTI ID:4820776

Zimmerman, W B

This work is an extension of a program exploiting isotopic mass and isotopic composition as probes for liquidstate and solid-state investigations to the study of the interaction of electromagnetic radiation with crystal lattices. The infrared absorption spectrum of thrn films (less than 0.1 mu ) of solid lithium hydride made of varying proportions of its separated isotopes (Li/sup 6/, Li/sup 7/, H/sup 1/, H/sup 2/) was obtaine d at room temperature in the wavelength region of 12.5 to 25 mu . The primary feature of the spectrum of the relatively pure materials Li/sup 6/H/sup 1/, Li/sup 6/H/sup 2/, Li/sup 7/H/sup 1/ , Li/sup 7/H/su p 1/, Li/sup 7/H/sup 2/ is a broad but definite absorption peak at the dispersion wavelengths 16.9, 22.2, sion wavelengths of Li//sup 6/H/sup 2/a and Li/sup 6/H/sup 1/Li/sup 7/sup H/sup 2/ and Li/sup 7/H/sup 1/, Li/sup 7/H/sup 1/ and Li/sup 6/H/sup 1/,Li/sup 7/H/sup 2/ and Li/sup 6/H/sup 2/ are: 1.31, 1.32, 1 respectively, which are in excellent accord with the respective ratios of the square root of the reduced masses: topic mass on the dispersion wavelength of an ionic crystal is in accord with a prediction of the elementary Born theory of lattice vibrations. The effect of isotopic composition on the infrared spectrum of mixtures of Li/sup 6/H/sub 1/ and Li/sup 6/H/sup 2/ appears to be complex. The dispersion wavelengths for the compositions Li/sup 6/STA72.1% H/sup 1/, 27.9% H/sup 2/!, Li/sup 6/STA57.0% H/sup 1/ H/sup 2/, Li/sup 6/STAl9.9% H/sup 1/, 80.1% H/sup 2/! are: 21.2, 21.4, 21.8 plus or minus 0. 02 mu , respectively. The ratios of the dispersion wavelengths of Li/sup 6/STA72.1% H/sup 1/, 27.9% H/sup 2/ ! and Li/sup 6/H/sup 1/,Li/sup 6/STA57.0% H/sup 1/, 43.0% H/sup 2/! and Li/sup 6/ STA72.1% H/sup 1/, 27.9% H/sup 2/!, Li/sup 6/STA19.9% H/sup 1/, 80.1% H /sup 2/! and Li/sup 6/STA57.0% H/sup 1/, 43.0% H/sup 2/! and Li/sup 6/STA72.1%H/sup 1/, 27.9%H/su p 2/!, Li/sup 6/STA19,9%H/sup 1/, 80.1%H/sup 2/! and Li/sup 6/STA57.0%H/ sup 1/, 43/. 0%H/sup 2/!, Li/sup 6/H/sup 2/ and Li/sup 6/STA19.9% H/sup 1/, 80.1% H/sup 2/ are: 1.25, 1.01, 1.02, 1.02 plus or minus 0.02, respectively, which are in disagreement with the respective ratios of the square roots of the average reduced masses: 1.09, 1.05, 1.10, 1.04. Therefore, the effect of isotopic composition on the dispersion wavelength of an ionic crystal cannot be explained simply by considering the composite film as being equivalent to one made up of isotopes with the average reduced mass.

• Research Organization: Michigan State Univ., East Lansing
• NSA Number: NSA-16-023691
• OSTI ID: 4820776
• Journal Information: Dissertation Abstr., Journal Name: Dissertation Abstr. Vol. Vol: 22
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ABSORPTION
BORN-VON KARMAN THEORY
CHEMISTRY
CRYSTALS
DEUTERIUM COMPOUNDS
DIFFRACTION
ELECTROMAGNETIC WAVES
ENRICHMENT
FILMS
FREQUENCY
HYDROGEN COMPOUNDS
IMPURITIES
INFRARED RADIATION
INTERACTIONS
IONS
ISOTOPE EFFECTS
ISOTOPES
LATTICES
LIQUIDS
LITHIUM 6
LITHIUM 7
LITHIUM HYDRIDES
MASS
MIXING
OSCILLATIONS
RADIATIONS
SOLIDS
SPECTRA