Molecule‐Enhanced Surface‐Enhanced Infrared Absorption Spectroscopy (MOSEIRA)

Abstract

Surface-enhanced infrared absorption spectroscopy (SEIRA) of methanol, ethanol, 1-propanol, and 2-propanol in thin films on planar silver halide (AgX) fibers under slow N(2) flow using 1 sec scans reveals structure in absorbance-time plots. The absorption intensities show extra enhancements (3x) in the absorbance (O--H stretch) ascribed to oligomers present at the AgX surface (molecule enhanced, thus MOSEIRA). This is above those due to amplification (40x, 20 reflections) and enhancement (30x, image dipoles or surface phonon polaritons). In the case of ethanol an excellent initial pentamer spectrum evolves over 8-10 min to a mixture of pentamer, tetramer, and trimer spectra that within another minute forms small oligomers and monomers. We use a new type of cell for infrared spectroscopy containing an AgX planar fiber. The optical configuration leads to a vicinal region at the surface defined by evanescent waves. Within this region are surface-induced organized species such as ethanol oligomers. The planar AgX fiber supports 20 reflections and transmits light over a wide visible-infrared wavelength range. Short scan times permit the study of volatile substrates or solvents, including the effects of solvent polarity.

Thin film infrared spectroscopy on planar silver halide: a new technology for water and other liquids in the mesoscopic domain

“…The loss of radiation is transformed into an absorption spectrum. the two cited above (direct observation of sample and small penetration depth) are (1) direct sample introduction into the cell (2) short acquisition time (0.1 s) (3) complete mid-IR spectra (4) no time lag (5) simple control of energy delivered to the sample (6) small sample sizes (sensitivity enhanced by surface enhanced infrared absorption, SEIRA) (7) sharp spectroscopic peaks, (8) unusually narrow absorption bands (9) broad spectral range (10) fiber easily removed and replaced (after cleaning). Numerous discoveries made with our cell using thin films of liquids have been reported.…”

N‐Alkylacylamides in Thin Films Display Infrared Spectra of 310‐, α‐, and π‐Helices with Visible Static and Dynamic Growth Phases

“…Signal (Sg) is a measurement of light flux defined with the instrument. [4,5] As far as we know, signal strength control has not been used prior to our work in IR spectroscopy. The resolution is 4 cm À1 and the bandwidth is 7900 cm…”

“…The signal intensity is set before the measurement of the background. Signal (Sg) is a measurement of light flux defined with the instrument 4. 5 As far as we know, signal strength control has not been used prior to our work in IR spectroscopy.…”

“…The TFIS of small molecule films on planar silver bromide–silver chloride (AgX)2 in a special cell3 has exploited the surprising surface enhancement of IR on planar AgX, with studies of the oligomerization of ethanol,4 acetonitrile,5 and the peptide model of NMF 6. TFIS has been used to make a spectroscopic identification of the oligomers of water [cyclic trimer, cyclic pentamer, cyclic hexamers (boat and chair), and bicyclic hexamers] 7.…”

Detection and Identification of Microorganisms in Mixed Cultures by Nanoparticle-Induced NanoSPR Enhanced FTIR Spectroscopy and Chemometrics

“…It is believed that the enhancement of the spectral signal mainly comes from the highly intensified local electromagnetic field caused by surface plasmon resonance (SPR) of the nanometer-thick metal film. Since the interaction between nanosized metal particles and incidental electromagnetic radiation creates strong localized SPR (LSPR) field around the particles, they also cause enhancement to the infrared absorption of molecules (on the order of 10~100) that are in close proximity to the particles, just like in the case of surface enhanced Raman scattering (Kosower et al, 2007).…”