Laser transfer of organic adsorbates: a test case using coronene surface patterns transferred with micrometer resolution to IR Windows

Abstract

It has been shown that molecules can be removed intact from surfaces by laser induced thermal desorption.(1) We show that this process can he used to transfer organic surface deposits across a vacuum gap to a transparent window such as NaCl for subsequent analysis by Fourier transform infrared spectrometry (FTIR). Experiments with thin film test patterns have revealed that a high degree of lateral resolution can be maintained in the transfer process. We attribute this to a strongly forward-peaked distribution of desorbed material. When the desorption wavelength is chosen such that the light is absorbed mainly by the substrate, a suitable power can be found to transfer all of the surface-deposited coronene to the transparent window. For example, rectangular spots of coronene can be transferred from a polished stainless steel surface, using 1.064 um radiation, with no more than a 10 mrad spread of the pattern and with almost no loss of material. © 1989, SPIE.