title: Surface-enhanced infrared absorption studies towards a new optical biosensor.
abstract: Reflectometric interference spectroscopy (RIfS), which is well-established in the visual regime, measures the optical thickness change of a sensitive layer caused, e.g., by binding an analyte. When operated in the mid-infrared range the sensor provides additional information via weak absorption spectra (fingerprints). The originally poor spectra are magnified by surface-enhanced infrared absorption (SEIRA). This is demonstrated using the broad complex fluid water band at 3300 cm-1, which is caused by superposition of symmetric, antisymmetric stretching vibration, and the first overtone of the bending vibration under the influence of H-bonds and Fermi resonance effect. The results are compared with a similar experiment performed with an ATR (attenuated total reflectance) set-up.
authors.affiliation: Institute of Physical and Theoretical Chemistry (IPTC), Eberhard Karls University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany.
authors.forename: Lothar
authors.initials: L
authors.lastname: Leidner
authors.affiliation: Institute of Physical and Theoretical Chemistry (IPTC), Eberhard Karls University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Stäb
authors.affiliation: Institute of Physical and Theoretical Chemistry (IPTC), Eberhard Karls University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany.
authors.forename: Jennifer T
authors.initials: JT
authors.lastname: Adam
authors.affiliation: Institute of Physical and Theoretical Chemistry (IPTC), Eberhard Karls University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany.
authors.forename: Günter
authors.initials: G
authors.lastname: Gauglitz
keywords: attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR); direct optical sensing; mid-infrared regime (MIR); reflectometric interference spectroscopy; surface-enhanced infrared absorption (SEIRA)