Our thanks are due to Mr. Melviil Weaver for his help in the mechanical construction and to Mrs. John W. Koch for her help in taltiilg measurements.

CROSS, W. G. and RAMSEY, N. F. 1950. Phys. Rev. 80, 929. GARVIN, R. L. 1953. Rev. Sci. Instr. 24, 618. SHANICLAND, R. S. 1937. Phys. Rev. 52, 414.

RECEIVED MAY 15, 1961. DEPARTAIENT OF PHYSICS, UNIVERSITY OF DELAWARE, NEIVARIC, DELAWARE, U.S.X.

FRANCK-CONDON FACTORS AND r-CENTROIDS FOR SOME BANDS OF THE SiO A 1 n - X l E + BAND SYSTEM

A partial (vl+v" < 8) array of Franck-Condon factors q , ~ , ~ ~ for the SiO (AIII-XIZ+) band system was computed to assist the interpretation of spectra of shock-excited powdered SiOz. Private requests for Franck-Condon factor arrays of this and other band systems of diatomic inorganic oxides which we have studied prompts us to report Franck-Condon factors, r-centroids, and wavelengths for SiO (AIII-XIZ+) in Table I.

TABLE I Franck-Condon factors q,*,ft, 7-centroids P , , , t l , and wavelengths X, ,~ , t r for the SiO AlII-X12+

band system

' J I I

5 0.043 0.157 0.03s 0.06s 1.385 1 479 1.518 1.550 2141.4* 2197.4 3259.7- 2323.0*

LEGBXD: P ~ ' ~ ' ' . ~u'u"(A), Xyry"(A). *Band wavelength calculated.

Can. J. Phys. Vol. 39 (1961)

Can

. J. P

hys.

Dow

nloa

ded

from

ww

w.n

rcre

sear

chpr

ess.

com

by

Dep

osito

ry S

ervi

ces

Prog

ram

on

11/1

7/14

For

pers

onal

use

onl

y.

1216 CANADIAN JOURNAL OF PHYSICS. VOL. 39. 1961

The wavelengths are mainly those of Jevons (1924); wavelengths of weak bands which he does not report have been calculated. The r-centroids were evaluated by methods disc~lssed by Nicholls and Jarmain (1956) and the Franc1;-Condon factors were calculated by the method of Fraser and Jarrnain (Fraser and Jarmain 1953; Jarmain and Fraser 1953; Fraser 1954) for Morse ~nolecules using the basic data for the transition tabulated by Herzberg (1950).

'The band system i~lvolves a moderately large change in internuclear separa- tion (Ar, = 0.11 A) and exhibits pri~nary and secondary Condon 'parabolae' in the Franck-Condon factor array. The entries for bands through which they pass are italicized. The eye estimate intensity distribution reported in Pearse and Gaydon's (1950) compilatio~l agrees well with the Franclr-Condon factor array.

The work has been supported in part by research grants from the National Research Council and the Ontario Research Foundation, and in part by con- tracts with the Air Force Cambridge Research Center, The Air Force Office of Scientific Research, and the Office of Naval Research.

FRASEII, P. A. 1954. Proc. Phys. Soc. A, 67, 939. FIIASER, P. A. and JARMAIN, W. R. 1953. Proc. Phys. Sac. A, 66, 1145. HERZBERG. G. 1950. S ~ e c t r a of diatomic molecules (D. Van Nostrand. New York). T A R M A I N . iV. R. and FR~SER. P. A. 1953. Proc. ~h;s . Soc. A. 66. 1153. . , ~ B \ I O N S , 'w. 1924. Proc. ~ d ~ . Sac. 106, 174. NICHOLLS, R. W. and JARMAIN, W. R. 1956. Proc. Phys. Sac. 69, 253. PEARSE, R. W. B. and GAYDON, A. G. 1950. The identilication of molecular spectra, 2nd

ed. (Chapman and Hall Ltd., London).

THE HALF-LIFE OF Srn1j3"

During the course of some ineasure~nents to determine the resonance integral of Sm15"(Wallter and Green 1961) it was observed, when correcting the product activity, S111155 for decay, that best I-esults were obtained using a half-life for Sm1j3 which was smaller by 2% than the best published value of 4 7 . l f 0.1 hours (Cork et al. 1958). Since we were concerned about the presence of impurities which would affect our resonance integral results we decided to investigate more fully the decay of SIII '~~.

The target material used consisted of a layer of S1ll203 (-140 pg/cn12 of Sm1j2) baked onto 0.0025 cm thick superpure aluminum foil (see Wallter

*Issued as A.E.C.L. No. 1280.

Can. J. Phys. Vol. 39 (1961)

Can

. J. P

hys.

Dow

nloa

ded

from

ww

w.n

rcre

sear

chpr

ess.

com

by

Dep

osito

ry S

ervi

ces

Prog

ram

on

11/1

7/14

For

pers

onal

use

onl

y.