The infrared multiple-angle incidence resolution spectroscopy (MAIRS) has been employed to analyze the hydrogen-terminated Si(111) 1 x 1-H surface. The new technique of infrared MAIRS provides two absorption spectra simultaneously on an identical sample, which separately reveal the surface-parallel and surface-normal vibration spectra. It has been exhibited in the present study that the infrared MAIRS technique is powerful to discuss some infrared key bands in terms of molecular orientation concerned with Si-H vibrational modes on the Si(111) 1 x 1-H surface with the use of the two spectra. (c) 2005 Elsevier B.V. All rights reserved.