Cryogenic stabilization of high vapor pressure samples for surface analysis under ultrahigh vacuum conditions

Abstract

A novel form of ultrahigh vacuum ͑UHV͒ cryogenic stabilization has been used to obtain high-resolution x-ray photoelectron spectroscopy ͑XPS͒ data from a complex amine, 1,8-bis͑dimethylamino͒naphthalene, whose solid phase exhibited at room temperature an unacceptably high rate of sublimation. Protonated versions of the amine exhibit hydrogen bonding. Electron spectroscopy for chemical analysis chemical shifts can be used to describe the strength and asymmetry of hydrogen bonding formed in proton sponge complexes. Analyzing the binding energy shifts of N ͑1s͒ induced by the presence of this hydrogen bonding required obtaining corresponding XPS spectra from the nonprotonated ͑reference͒ sample, but the reference sample sublimes under even moderate vacuum conditions. The combined results suggest that other high vapor pressure materials, particularly those that were previously considered to be too corrosive for routine analysis, can be cryogenically stabilized for surface analysis under similar UHV conditions.

Antifouling character of ‘active’ hybrid xerogel coatings with sequestered catalysts for the activation of hydrogen peroxide

“…A more likely scenario is that the two peaks represent primary ammonium (404.5 eV) and primary amino (402.6 eV) groups from the APTES residues on the xerogel surface. The 1.9 eV separation between the two N(1s) peaks is similar to the 2.5 eV separation observed between the N(1s) peaks for a protonated (402.0 eV) and unprotonated (399.5 eV) dimethylamino group in protonated 1,8-bis(dimethylamino)-naphthalene (DMAN-HBr) (Bruckner et al 1999) (Chart 2). Unprotonated DMAN shows a single N(1s) peak at 399.5 eV.…”

Optimization of cryo‐XPS analyses for the study of thin films of a block copolymer (PS‐PEO)

“…In an attempt to avoid the omnipresent oxidation layer at reactive metal surfaces, Love et al used cryogenic cooling to keep surfaces in the metallic state 31. The same principle was applied by Bruckner et al on complex amines with high rates of sublimation 32. In the same way, Cardenas and Sjoberg studied the sorption of monoions onto TiO 2 crystal 33.…”