Les problèmes de physique du solide posés par l'émission photoélectrique

Vernier, P.

doi:10.1051/jphys:0196500260208700

Cited by 4 publications

(1 citation statement)

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“…This paper is concerned with measurements a t trialkali antimonide cathodes. The interesting results of metal cathodes [29] especially that of plasmon processes [30] are beyond the present consideration.…”

Section: Tho Vector Effectmentioning

confidence: 98%

Experimental evidence of the angular dependence of electron excitation in photoemission

Hora

1971

Phys. Stat. Sol. (a)

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The dependence of the photoemission from thin layers of trialkali antimonide on the direction of polarisation of obliquely incident light (vector effect) was measured a t temperatures between 80 and 300 "K. At low temperatures a decrease of the ratio of polarisation yield is found a t increasing light intensities up to I = 1015 photons/cm2 s of 1.9 eV photon energy. The decrease is nearly parallel to the measured decrease of the quantum yield Q of the relation Q -I-1P. This change is related t o a n increase of the surface potential of the cathode and to filling of surface traps by photoelectrons. The change of K is describable by decreasing the exit cone of the photoelectrons. The stronger decrease of K than it could be explained by that of Q with I indicates an angular dependence of the excitation process of the electrons in the cathode. A qualitative conclusion of a Compton-like preferential direction somehow perpendicular t o the E-vector of the light is given.Es wurde die Abhangigkeit der Photoemission aus dunnen Schichten von Tri-Alkaliantimonid in Abhangigkeit von der Polarisation des schrag einfallenden Lichtes (Vektoreffekt) bei Temperaturen zwischen 80 und 300 " K gemessen. Bei niedrigen Temperaturen wurde ein Abfall des Polarisationsverhaltnisses mit steigender Lichtintensitat bis zu I = 1015 Photonen/cm2 s mit 1,9 eV Photonenenergie gefunden. Der Abfall verlauft nahezu parallel mit dem gemessenen Abfall der Quantenausbeute Q mit der Beziehung Q -1-1/2. Die Anderung ist mit einem Ansteigen des Oberflachenpotentials der Katode und dem Fullen von Oberflachenhaftstellen durch Photoelektronen verbunden. Die Anderung von K ist mit der Verkleinerung des Austrittskegels der Photoelektronen erklarbar. Der Abfall von K , der starker ist, als der durch die AbhLngigkeit von Q von 1 erklarbare, weist auf eine Winkelabhangigkeit des Anregungsprozesses der Elektronen in der Katode hin. Eine qualitative SchluBfolgerung auf eine Compton-ahnliche Vorzugsrichtung, etwa senkrecht zum E-Vektor des Lichts, wird angegeben.

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Section: Tho Vector Effectmentioning

confidence: 98%

Experimental evidence of the angular dependence of electron excitation in photoemission

Hora

1971

Phys. Stat. Sol. (a)

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The Anomalous Vectorial Photoemission from a Cesium‐Antimony Layer

Hora

Kantlehner

1966

Physica Status Solidi (b)

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The photoemission from a transparent cesium‐antimony layer is measured. A special arrangement of the cell allows a 75° angle of incidence of the light, so that the reflected and transmitted intensities can be determined simultaneously. With an E‐vector perpendicular or parallel to the plane of incidence, the absolute quantum yields Q are measured as functions of the absorbed light. In this way it is possible, apparently for the first time, to determine the absolute ratios of polarization yield Kabs = Q⊥/Q∥ for large angles of incidence. With glass‐side illumination the vector effect is anomalous (as in previous results), having maximum Kabs values of 1.7 in the region of phonon energies of 2.2 eV. By contrast, the Kabs values are within 10% of unity with vacuum‐side illumination. Besides the virtual absence of the vector effect, there is a small systematic variation around unity. This shows that the electron excitation process is almost isotropic in the direction opposite but parallel to the motion of the photons. Only in the forward direction can anisotropy with a preferred direction perpendicular to the E‐vector be deduced. This is analogous to the Compton effect and may be explained as a predominance of indirect transitions. The ratio of the probability of indirect to direct transitions is estimated, and from this the band structure beyond the minima may be determined.

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