The application of infrared synchrotron radiation to the study of interfacial vibrational modes
Synchrotron radiation provides an extremely bright broad-band source in the infrared which is ideally suited to the study of surface and interface vibrational modes in the range 50--3,000 cm{sup {minus}1}. Thus it covers the important range of molecule-substrate interactions, as well as overlapping with the more easily accessible near-ir region where molecular internal modes are found. Compared to standard broadband infrared sources such as globars, not only is it 1,000 times brighter, but its emittance matches the phase-space of the electrochemical cell leading to full utilization of this brightness advantage. In addition, the source is more stable even than water-cooled globars in vacuum for both short-term and long-term fluctuations. The authors summarize the properties of synchrotron radiation in the infrared, in particular pointing out the distinct differences between this and the x-ray region. They use experimental data in discussing important issues of signal to noise and address the unique problems and advantages of the synchrotron source. Thus they emphasize the important considerations necessary for developing new facilities. This analysis then leads to a discussion of phase-space matching to electrochemical cells, and to other surfaces in vacuum. Finally they show several examples of the application of infrared synchrotron radiation to surface vibrational spectroscopy. The examples are for metal crystal surfaces in ultra-high vacuum and include CO/Cu(100) and (111) and CO/K/Cu(100). The experiments show how the stability of the synchrotron source allows subtle changes in the background to be observed in addition to the discrete vibrational modes. These changes are due to electronic states induced by the adsorbate. In some cases the authors have seen interferences between these and the discrete vibrational modes, leading to a breakdown of the dipole selection rules, and the observation of additional modes.
- Research Organization:
- Brookhaven National Lab., Upton, NY (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 10163315
- Report Number(s):
- BNL-48966; CONF-921277-1; ON: DE93015393; TRN: 93:001647
- Resource Relation:
- Conference: NATO advanced research workshop,Maderia (Portugal),19 Dec 1992; Other Information: PBD: [1992]
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
43 PARTICLE ACCELERATORS
SYNCHROTRON RADIATION
INFRARED RADIATION
CARBON MONOXIDE
INTERFACES
OSCILLATION MODES
VIBRATIONAL STATES
PRODUCTION
METALS
BRIGHTNESS
FLUCTUATIONS
ELECTROCHEMICAL CELLS
SURFACES
SPECTROSCOPY
BREAKDOWN
COPPER
POTASSIUM
NSLS
400201
430303
CHEMICAL AND PHYSICOCHEMICAL PROPERTIES
EXPERIMENTAL FACILITIES AND EQUIPMENT