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Title: Stand-alone polarization-modulation infrared reflection absorption spectroscopy instrument optimized for the study of catalytic processes at elevated pressures

This article describes the design and construction of a compact, “user-friendly” polarization-modulation infrared reflection absorption spectroscopy (PM-IRRAS) instrument at the Center for Functional Nanomaterials (CFN) of Brookhaven National Laboratory, which allows studying surfaces at pressures ranging from ultra-high vacuum to 100 Torr. Surface infrared spectroscopy is ideally suited for studying these processes as the vibrational frequencies of the IR chromophores are sensitive to the nature of the bonding environment on the surface. Relying on the surface selection rules, by modulating the polarization of incident light, it is possible to separate the contributions from the isotropic gas or solution phase, from the surface bound species. A spectral frequency range between 1000 cm -1 and 4000 cm -1 can be acquired. While typical spectra with a good signal to noise ratio can be obtained at elevated pressures of gases in ~2 min at 4 cm -1 resolution, we have also acquired higher resolution spectra at 0.25 cm -1 with longer acquisition times. By way of verification, CO uptake on a heavily oxidized Ru(0001) sample was studied. As part of this test study, the presence of CO adsorbed on Ru bridge sites was confirmed, in agreement with previous ambient pressure X ray photoelectronmore » spectroscopy studies. In terms of instrument performance, it was also determined that the gas phase contribution from CO could be completely removed even up to pressures close to 100 Torr. A second test study demonstrated the use of the technique for studying morphological properties of a spin coated polymer on a conductive surface. Note that this is a novel application of this technique. In this experiment, the polarization of incident light was modulated manually (vs. through a photoelastic modulator). It was demonstrated, in good agreement with the literature, that the polymer chains preferentially lie parallel with the surface. This PM-IRRAS system is small, modular, and easily reconfigurable. It also features a “vacuum suitcase” that allows for the integration of the PM-IRRAS system with the rest of the suite of instrumentation at our laboratory available to external users through the CFN user proposal system.« less
Authors:
 [1] ;  [2] ;  [1] ; ORCiD logo [1] ;  [1] ; ORCiD logo [1] ; ORCiD logo [1]
  1. Brookhaven National Lab. (BNL), Upton, NY (United States). Center for Functional Nanomaterials (CFN)
  2. Brookhaven National Lab. (BNL), Upton, NY (United States). Chemistry Dept.; King Abdullah Univ. of Science and Technology, Thuwal (Saudi Arabia). Saudi Basic Industries Corporation (SABIC) and Controlled Release and Delivery Lab. (CRD)
Publication Date:
Report Number(s):
BNL-203375-2018-JAAM
Journal ID: ISSN 0034-6748
Grant/Contract Number:
SC0012704
Type:
Accepted Manuscript
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 88; Journal Issue: 10; Journal ID: ISSN 0034-6748
Publisher:
American Institute of Physics (AIP)
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; 46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 47 OTHER INSTRUMENTATION; 36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Materials; Metals; Spectroscopy; Metallurgy; Chemical analysis; Transition metals; Optical metrology; Thin film deposition; Materials analysis; Spectra
OSTI Identifier:
1430855
Alternate Identifier(s):
OSTI ID: 1399286