Abstract

The reflectances of evaporated films of Li were measured as functions of angle of incidence for photon energies between 3 and 10.7 eV, and were analyzed, by use of Fresnel’s equations, to determine the optical constants n and k for each energy. Above 6 eV, measurements with photons incident on both vacuum and substrate surfaces gave the same values of n and k within experimental limits of about ±5%. Below 6 eV, values of n and k obtained from the analysis were not reproducible; they depend in a complex way on film thickness, light polarization, and surface structure. Failure of the analysis below 6 eV is attributed to surface-roughness effects on the R (θ) curves, which are not accounted for in Fresnel’s equations. These effects are believed to be small above 6 eV. The dielectric function 1 and 2 and the energy-loss function Im(− 1/) were determined from n and k for photon energies above 6 eV. The plasma energy of Li, as determined from the condition 1 (ω) = 0, is 6.7 eV; and the plasma loss peak in Im(−1/) is centered at 7.1 eV. In contrast to results for the heavy alkali metals K, Rb, and Cs, no evidence was found for an optical-absorption peak in 2 in the spectral region above the plasma frequency.

© 1974 Optical Society of America

Full Article  |  PDF Article
Related Articles
Ellipsometer Study of Anomalous Absorption in Very Thin Dielectric Films on Evaporated Metals*

N. M. Bashara and D. W. Peterson
J. Opt. Soc. Am. 56(10) 1320-1331 (1966)

Optical Properties of Potassium for Photons of Energy 3.96 to 9.69 eV*

J. C. Sutherland and E. T. Arakawa
J. Opt. Soc. Am. 58(8) 1080-1083 (1968)

Extinction Coefficient and Imaginary Part of the Dielectric Constant for Sodium and Potassium above the Plasma Energy*

J. C. Sutherland, R. N. Hamm, and E. T. Arakawa
J. Opt. Soc. Am. 59(12) 1581-1583 (1969)

References

You do not have subscription access to this journal. Citation lists with outbound citation links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Cited By

You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Figures (7)

You do not have subscription access to this journal. Figure files are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Tables (1)

You do not have subscription access to this journal. Article tables are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Equations (2)

You do not have subscription access to this journal. Equations are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription