Incoherent broad-band cavity-enhanced absorption spectroscopy

A new highly sensitive method for incoherent broad-band cavity-enhanced absorption measurements of gaseous samples, using a white-light source is demonstrated. The light of a short-arc Xe-lamp transmitted by an optically stable cavity is dispersed with a grating monochromator and detected by a sensitive photodiode-array. The technique is a development of the previously published principle of cavity-enhanced absorption spectroscopy. The method is characterized by great experimental simplicity, high sensitivity, and high temporal resolution. These features are demonstrated on basis of the b¹∑^g₊(v′ = 2) ← X³∑^g_-(v″ = 0) absorption transition of molecular oxygen and the S₁, v' ← S₀ absorption spectrum of gaseous azulene at its vapour pressure at room temperature.