Infrared studies of sub-monolayer methylamine and trimethylamine adsorption on Ni(111)

• Published in: Surface science Vol. 427; pp. 282 - 287
• Main Authors: Nunney, T.S., Birtill, J.J., Raval, R.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Lausanne Elsevier B.V 01.06.1999; Amsterdam Elsevier Science; New York, NY
• Subjects: Chemisorption; Chemistry; Condensed matter: structure, mechanical and thermal properties; Dynamics; vibrations; Exact sciences and technology; General and physical chemistry; Methylamines; Nickel; Physics; Reflection absorption IR spectroscopy; Single crystal surfaces; Solid-fluid interfaces; Solid-gas interface; Surface and interface dynamics and vibrations; Surface physical chemistry; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Vibrations of adsorbed molecules; Chemisorption; Methylamines; Nickel; Single crystal surfaces; Reflection absorption IR spectroscopy; Vibrations of adsorbed molecules; Gas solid adsorption; Amine; Organic adsorbate; Gas solid interface; Metallic adsorbent; Transition metal; Infrared spectrum; Experimental study; Vibrational mode
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/S0039-6028(99)00280-0

The adsorption of monomethylamine and trimethylamine on Ni(111) has been studied using reflection absorption infra-red spectroscopy (RAIRS). At 110 K, both molecules are found to chemisorb molecularly and to retain their gas-phase symmetries at the surface. Methylamine possesses an adsorption site symmetry of C s in which the NH 2 unit is held parallel to the surface plane and the methyl group is tilted with respect to the surface normal. Trimethylamine possesses C 3v symmetry upon adsorption, with the c 3 axis aligned along the surface normal. The high sensitivity RAIR data allow a peculiar feature of methylamines to be probed: the lone pair on the nitrogen gives rise to inequivalence in the CH bonds of the methyl unit, leading to the creation of one much weaker C–H bond that produces a decoupled vibration at an unusually low stretching frequency.