W. Pong

Photoelectric emission from copper phthalocyanine films

Photoemission measurements on copper phthalocyanine films were made for photon energies of 7–23 eV. The spectral quantum yield was determined. The energy distribution of the photoemitted electrons for photon energies above 16 eV shows structure characteristic of the density of states. In addition, the attenuation length of electrons photoinjected into copper phthalocyanine was measured. For electrons of approximately 1.5 eV above the vacuum level, the electron‐electron mean free path is estimated to be 11 A.

Vacuum ultraviolet photoemission studies of nucleic acid bases

The spectral quantum yields of adenine, thymine, cytosine, and uracil films were measured at photon energies of 7 to 23 eV. In addition, photoelectron‐energy‐distribution measurements were made at 21.2 eV. The photoelectron spectra exhibit features which can be associated with density‐of‐states structures below the vacuum level. The difference between the observed photoemission threshold of a solid film and the calculated energy of the highest occupied orbital for the isolated molecule is found to be 1.5–2.0 eV.

Attenuation Length for Photoelectrons in Metal Films

Attenuation length of vacuum UV photoexcited electrons in evaporated metal films, observing lack of dependence on photon energy

Electroluminescence in Al‐Al2O3‐Au diodes

Thin‐film diodes composed of Al‐Al2O3‐Au films can be made to emit light under applied voltages. The spectral intensity of the electroluminescence was measured in the wavelength range 2000–6000 A for different diode voltages. In this spectral range, the intensity was found to decrease nearly exponentially with increasing photon energy for a given voltage. The results also indicate that as the intensity of the short‐wavelength emission is enhanced with increasing diode voltage above approximately 4 V, there is a corresponding decrease in intensity in the long‐wavelength region. An attempt is made to explain the results in terms of a band model of the oxide.

Photoemission studies of LaF 3

Quantum-yield and photoelectron-energy-distribution measurements on evaporated LaF3 films have been made in the photon energy range 10–27 eV. Photoemission from the F−2p valence band indicates a bandwidth of 3.5 ± 40.3 eV and a photoelectric threshold of 11.7 ± 0.3 eV. The photoelectron spectra exhibit features that can be identified as density-of-states structures of the valence and conduction bands. An attempt is made to relate these structures to the initial and final states of ultraviolet transitions.

Escape Depth for Excited Photoelectrons in KBr Films

Attenuation length of excited photoelectrons in evaporated potassium bromide films by measuring quantum yield as function of film thickness

Effect of Boundary Scattering on Photoemission from Thin Films

A one-dimensional escape-probability function is derived for electrons optically excited in a thin film. The effects of electron–electron scattering, electron–phonon scattering, and finite reflection at the film interfaces are taken into account. Numerical examples are presented to illustrate the dependence of the escape probability on the film thickness and the amount of back scattering from the substrate. An application to photoemission from thin metal films is discussed.

Photoemission from amorphous and metallic selenium in the vacuum ultraviolet.

Photoemission of vacuum evaporated, amorphous and metallic selenium films in spectral range from 2000 to 1100 angstroms

Attenuation length measurements of photoexcited electrons in CuBr films.

The attenuation length of photoexcited electrons in evaporated layers of CuBr was estimated by measuring the photoemission yield as a function of thickness. The attenuation length was found to be less than the optical absorption depth at photon energies between 8 and 11 eV. At hν=9.7 eV, the attenuation length is approximately 51 A.

Exciton‐Induced Photoemission from KCl Films

The photoelectric yield of evaporated KCl films was measured for photon energies from 7 to 14 eV. A gradual rise of photoelectron emission with time was observed under steady ultraviolet excitation of approximately 8 eV. In the presence of strong biasing radiation (visible light), the gradual rise of photomission did not appear. An attempt is made to explain the transient enhancement in terms of electron emission from new F centers formed by excitons.