A novel approach for ultra-sensitive molecular detection — Laser induced fluorescence spectroscopy in an electrospray stream

Abstract

A novel approach for ultra-sensitive molecular detection achieving a detection limit of 2.02×10−15M, corresponding to 55 rhodamine 6G molecules within the probe volume, was obtained by minimizing the light scattering barriers between the probe volume and the detection equipment. The spectroscopic system consists of an electrospray stream for sample introduction, an argon ion laser for molecular excitation, a lock-in amplifier for beam modulation, a 10X magnification objective for emission collection, a spectral filter for emission selection, and a cooled photo-voltaic device for photon detection.