Laser-induced atomic adsorption: A mechanism for nanofilm formation
Laboratório de Espectroscopia Ótica - DF, Universidade Federal da Paraíba - Caixa Postal 5086, 58051-900 João Pessoa, PB, Brazil
Received: 29 July 2013
Accepted: 31 October 2013
We demonstrate and interpret a technique of laser-induced formation of thin metallic films using alkali atoms on the window of a dense-vapour cell. We show that this intriguing photo-stimulated process originates from the adsorption of Cs atoms via the neutralization of Cs+ ions by substrate electrons. The Cs+ ions are produced via two-photon absorption by excited Cs atoms very close to the surface, which enables the transfer of the laser spatial intensity profile to the film thickness. An initial decrease of the surface work function is required to guarantee Cs+ neutralization and results in a threshold in the vapour density. This understanding of the film growth mechanism may facilitate the development of new techniques of laser-controlled lithography, starting from thermal vapours.
PACS: 34.35.+a – Interactions of atoms and molecules with surfaces / 32.80.Fb – Photoionization of atoms and ions / 73.30.+y – Surface double layers, Schottky barriers, and work functions
© EPLA, 2013