Accession Number:

ADA193748

Title:

Interfacial Infrared Vibrational Spectroscopy.

Descriptive Note:

Technical rept.,

Corporate Author:

UTAH UNIV SALT LAKE CITY DEPT OF CHEMISTRY

Personal Author(s):

• Pons, Stanley
• Foley, John K.
• Russell, Joel
• Seversen, Mark

Report Date:

1986-07-30

Pagination or Media Count:

78.0

Abstract:

Vibrational spectra of species on or near metal surfaces are subject to a unique surface selection rule due to the physics of reflection of radiation from a highly conducting surface. As shown in Fig. 1, s-polarized radiation electric vector perpendicular to the plane of incidence at all angles of incidence undergoes a phase shift close to 180 C. P-polarized radiation electronic vector in plane of incidence has a phase change upon reflection which varies with the angle of incidence as also shown in Fig. 1. Light reflected from a metal surface combines with the incident light to form a standing wave electric field whose intensity is shown in Fig. 2. The mechanism for absorption of infrared radiation requires a coupling of the electric field with a molecular vibration. Since the intensity of the standing wave electric field parallel to the surface is near zero, only those modes of a species near the metal surface which produce a fluctuation in the dipole moment with component normal to the surface can absorb energy.

Descriptors:

• *INFRARED SPECTROSCOPY
• *MOLECULAR VIBRATION
• *VIBRATIONAL SPECTRA
• *SURFACE CHEMISTRY
• *ELECTROCHEMISTRY
• ANGLE OF INCIDENCE
• DIPOLE MOMENTS
• ELECTRIC FIELDS
• INFRARED RADIATION
• INTERFACES
• METALS
• PHASE SHIFT
• PHASE TRANSFORMATIONS
• RADIATION ABSORPTION
• SPECTROSCOPY
• STANDING WAVES
• SURFACES
• RAMAN SPECTRA

Subject Categories:

• Atomic and Molecular Physics and Spectroscopy
• Physical Chemistry

Distribution Statement:

APPROVED FOR PUBLIC RELEASE