Depth Resolution in Photoelectron Microscopy of Organic Surfaces. The Photoelectric Effect of Phthalocyanine Thin Films

Abstract

Abstract— The application of photoelectron microscopy as a general method of imaging organic and biological surfaces requires a knowledge of the photoelectric effect of very thin organic films. In this study, low magnification images of a 7 Å thick pattern of copper phthalocyanine were obtained, demonstrating that it is possible to visualize a monolayer of organic compound in photoelectron microscopy. Relative photoelectron currents were measured for a series of copper phthalocyanine films ranging in thickness up to 1900 Å. The relative photoelectron currents were independent of temperature (90–298°K), suggesting that electron‐electron and not electron‐phonon scattering is the dominant mechanism. The photoelectric properties measured are determined primarily by the large organic ring structure and not the central metal atom, as evidenced by the fact that substitution of metal‐free phthalocyanine for copper phthalocyanine did not substantially alter the values of observed photoelectron currents. An analysis of the data indicates the depth resolution is 15 ű 5 Å, and equals the electron mean free path. This very good depth resolution is a result of the low kinetic energy associated with electrons released by irradiation near the photoemission threshold.

Photoelectron imaging of cells: photoconductivity extends the range of applicability

“…where d is the sample thickness and the factors P2 and P4, which are independent of z, are included in the coefficient B (Burke et al, 1974;Sommer and Spicer, 1965). Eq.…”

Photoelectron Quantum Yields of the Amino Acids

“…Y. ), purified by vacuum zonal sublimation as described elsewhere (Burke et al, 1974). This compound was chosen for its stability and because consistently uniform samples are relatively easy to prepare by vacuum sublimation.…”

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<title>Photoelectron Microscopy Of Biological Surfaces Excitation Source Brightness Requirements</title>

“…These are very preliminary low magnification images. Several additional reports examine specific aspects of PEM applications to organic and biological surfaces (3)(4)(5)(6)(7)(8)(9)(10). Metallurgical ap plications are reviewed elsewhere (H).…”