| Abstract
| - A new generation waveguide spectrometer with broadbandcoupling capabilities has been developed. As opposed toprevious devices, this attenuated total reflection (ATR)spectrometer is much simpler in design, is more chemically robust, and transmits light down to at least 400 nm.The attenuated total reflection element consists of a single-mode, planar integrated optical waveguide fabricated bydip-coating a ∼300 nm thick, sol−gel composite layer ona glass substrate. A commercially available prism is usedas the incoupler with an integral holographic diffractiongrating acting as the dispersive outcoupling element. Thetransmission of narrow band-pass filters was used tocompare the response of the waveguide spectrometer tothat of a conventional transmission instrument. Spectralresolution was assessed by measuring the fwhm of variouslaser lines, which were found to range from 0.5 to 1.3nm. The measured limits of detection for the waveguidespectrometer from 400 to 600 nm are 8.0 and 10.1milliabsorbance units for TE and TM polarizations, respectively. Finally, to demonstrate the application of thistechnology to a molecular film confined to a solid−liquidinterface, visible ATR spectra of an adsorbed submonolayer of horse heart cytochrome c were acquired. Aprocedure to correct the waveguide spectra for the wavelength dependence in ATR path length is described.
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