On The Band Spectrum of Calcium Hydride
- 1 January 1927
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review B
- Vol. 29 (1), 97-111
- https://doi.org/10.1103/physrev.29.97
Abstract
An arc of calcium burning in hydrogen at low pressure emits numerous bands in the region 6000-7000A. This spectrum was photographed at high dispersion and two groups of bands, shading toward the violet may be distinguished: the A groups with heads at , 7028, 6921, 6903 and the B groups with heads at , 6382. In addition to these, the arc emits an isolated C group—a single band in the ultra-violet at . This group is identical with a band of calcium hydride recently studied by R. S. Mulliken. The structures of A, B and C are very different. The A group forms a doublet system (, ) of branches. The bands of the B group have a similar structure to that of the violet cyanogen bands, signified by doublet , and , branches. The C group consists of a single band having branches. In all bands the series deviate largely from polynomials of second degree. Thus, in B and C there is a remarkable "red-shift" of high numbered lines, accompanied by a sharp cut-off in their intensity. From combinations found between the branches, conclusions are reached regarding the spectral terms in CaH. The A, B and C groups have a common final () electronic term with a rotational doubling (, ). The initial state of A forms an electronic doublet (, ) with the emission electron in a -orbit (, ), thus explaining the appearance of branches in A. In B (initial) there is again a rotational doubling (, ). In C (initial) only one component is present (, ). The departure from half-integral quantum numbers in C is avoided by accepting a large Kratzer's linear term . The nuclear spacings in the CaH molecule are not in correlation with their vibration frequencies, violating a rule by Birge and Mecke. A comparison of the A group with the spectra of ZnH, CdH and HgH shows several interesting parallels, confirming the theory of Mulliken regarding these spectra.
Keywords
This publication has 12 references indexed in Scilit:
- The Absorption Spectra of Some Hydride Compounds in the Ultra-VioletPhysical Review B, 1926
- The Magnesium Hydride Band SpectrumThe Astrophysical Journal, 1926
- Über die Bandenspektra von AluminiumThe European Physical Journal A, 1925
- Zum Aufbau der BandenspektraThe European Physical Journal A, 1925
- A Band of Unusual Structure Probably Due to a Highly Unstable Calcium Hydride MoleculePhysical Review B, 1925
- The Emission Spectrum of Water-VaporThe Astrophysical Journal, 1924
- Zur Theorie der BandenspektrenZeitschrift für Physik, 1923
- Die Feinstruktur einer Klasse von BandenspektrenAnnalen der Physik, 1923
- On the Spectra of Some of the Compounds of the Alkaline EarthsThe Astrophysical Journal, 1909
- Sun-Spot Bands Wiuch Appear in the Spectrum of a Calcium Arc Burning in the Presence of HydrogenThe Astrophysical Journal, 1908