Quantitative detection of singlet O_2 by cavity-enhanced absorption

Abstract

A method for the practical determination of the absolute concentration of single (a 1 D g ) oxygen is discussed. The method is based on sensitive off-axis integrated-cavity-output spectroscopy (ICOS). Off-axis ICOS allows narrowband, continuous-wave lasers to be used in conjunction with optical cavities to record sensitive absorption measurements. The details of the method as well as spectroscopic data confirming the first observation of the ͑1, 0͒ band of the b Oxygen has systems in the near-infrared (a 1 D g X 3 S g 2 ) and the visible (b 1 S g 1 X 3 S g 2 ) regions that are atypically weak but are important to the radiative properties of the atmosphere. As a result, these transitions are well characterized spectroscopically and are the focus of much recent work.

High-precision measurements of water isotopes using laser absorption spectroscopy

“…Injected water samples were vaporized in the sample injection block and introduced into the optical cavity evacuated with a diaphragm pump through a PTFE transfer tube. Principles of the OA-ICOS technique are described in the literature (e.g., Paul et al, 2001;Baer et al, 2002;Williams et al, 2004).…”

Quantitative determination of singlet oxygen density and temperature for Oxygen-Iodine Laser Applications

“…We have recently reported measurements of the (1,0) band of the Noxon system ðb 1 R þ g a 1 D g Þ near 1505 nm [15]. The current measurements near 1910 nm have two key advantages over this earlier work.…”

“…The rovibrational Schrö dinger equation has been solved in the case-b limit and excellent agreement with the vibrational energies of the oxygen potential energy surfaces has been obtained. These calculations were then used to solve for the quadrupole transition probability and a value of 1.26 · 10 À3 s À1 has been calculated [15]. The transition probability is then used to calculate a peak absorption cross-section shown in Fig.…”

“…A second advantage of exploiting the (0,0) band is that less reflective cavity optics may be used. In this work, we used cavity optics with 841 ppm loss at 1910 nm (R = 99.9159%) compared with the 14 ppm loss optics used previously at 1505 nm (R = 99.9986%) [15]. Therefore, the cavity used in the present work is more immune to extraneous cavity losses (e.g.…”

“…In this Letter, we report the application of off-axis integrated cavity output spectroscopy (off-axis ICOS) to address this problem by directly measuring the absorption spectra of singlet oxygen near 1910 nm by exploiting the (0,0) band of the Noxon system ðb 1 R þ g a 1 D g Þ. Our earlier work focused on measuring the overtone (1,0) band of this spectroscopic system around 1505 nm [15], and the two approaches are contrasted below.…”