Skip to main content

Optical Considerations for Infrared Reflection Spectroscopic Analysis in the C-H Stretching Region of Monolayer Films at an Aqueous/Metal Interface

Buy Article:

$29.00 plus tax (Refund Policy)


This paper describes the optical analysis, construction, testing, and application of a cell for measuring in situ IR reflection spectra in the C-H stretching region of monolayer films of long-chain alkanethiolates on evaporated Au films beneath a thin overlayer (∼1 μm) of aqueous solution. The cell facilitates the interchange of sample (monolayer-coated) and reference substrates—a major improvement over previous designs. This allows the acquisition of an IR reflection spectrum of a monolayer without the application of electrochemical or polarization-modulation methods. The optical properties of the cell are analyzed within the context of classical electromagnetic theory; the effects of angle of incidence, solution layer thickness, and solution composition (H2O and D2,O) and the refractive indices of the IR-transparent window material on the observed spectrum are specifically examined. Calculations of both the mean-square electric fields and the reflection spectra for a monolayer of octadecanethiolate on Au are presented. From these results, conditions to achieve high surface detectability are identified, and optically induced alterations in the intensities and shapes of the monolayer spectrum are delineated. Spectra for the same monolayer are measured to test these predictions as well as to assess the practical limitations of the experimental technique.

Keywords: Infrared; Reflectance spectroscopy; Spectroscopic techniques; Surface analysis

Document Type: Research Article


Affiliations: Ames Laboratory-U.S. Department of Energy and Department of Chemistry, Iowa State University, Ames, Iowa 50011

Publication date: January 1, 1992

More about this publication?

Access Key

Free Content
Free content
New Content
New content
Open Access Content
Open access content
Subscribed Content
Subscribed content
Free Trial Content
Free trial content
Cookie Policy
Cookie Policy
ingentaconnect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more