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Mean transverse energy of ultrananocrystalline diamond photocathode

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journal contribution
posted on 24.05.2019, 00:00 authored by Gongxiaohui Chen, Gowri Adhikari, Linda Spentzouris, Kiran Kumar Kovi, Sergey Antipov, Chunguang Jing, W. Andreas Schroeder, Sergey V. Baryshev
Nitrogen incorporated ultrananocrystalline diamond [(N)UNCD] could be an enabling material platform for injector photocathode applications due to its high emissivity. While the quantum efficiency (QE) of UNCD was reported by many groups, no experimental measurements of the intrinsic emittance/mean transverse energy (MTE) have been reported. Here, MTE measurement results for an (N)UNCD photocathode in the photon energy range from 4.41 to 5.26 eV are described. The MTE demonstrates no noticeable dependence on the photon energy, with an average value of 266 meV. This spectral behavior is shown not to be dependent upon physical or chemical surface roughness and inconsistent with low electron effective mass emission from graphitic grain boundaries but may be associated with emission from spatially confined states in the grain boundaries. The combined effect of low and constant MTE and high QE, which increases with respect to the excess laser energy, may pave the way for bright UNCD photocathodes for electron injectors.


This project was supported by the NSF Grant No. NSF-1739150, DOE SBIR program Grant No. DE-SC0013145 and NSF Grant No. PHYS-1535279. The use of the Center for Nanoscale Materials, an Office of Science user facility, was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. S.V.B. was supported by funding from the College of Engineering, Michigan State University, under the Global Impact Initiative.


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Chen, G. X. H., Adhikari, G., Spentzouris, L., Kovi, K. K., Antipov, S., Jing, C. G., . . . Baryshev, S. V. (2019). Mean transverse energy of ultrananocrystalline diamond photocathode. Applied Physics Letters, 114(9). doi:10.1063/1.5084167


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