Surface enhanced infrared absorption spectroscopy (SEIRA) using external reflection on low-cost substrates

A novel approach for spectroscopic trace analysis is introduced by combining surface enhanced infrared absorption (SEIRA) spectroscopy with external reflection techniques on disposable inexpensive substrates. SEIRA-active surfaces produced by electrochemical deposition of silver on smooth metal surfaces and glass improve the sensitivity of IR reflection measurements significantly since the infrared absorption of organic substances such as p-nitrobenzoic acid is considerably increased in the vicinity of rough noble metal surfaces. The enhancement properties of thus prepared substrates are characterized and compared using IR-spectroscopy. These low-cost substrates used in single- and multiple external reflection arrangements, respectively, yield a significant increase of the detection level compared to conventional reflection absorption infrared spectroscopy (RAIRS) up to one order of magnitude. Hence, a notable step towards a wide-spread application of SEIRA in routine IR reflection analysis is presented.