Fixed-frequency cavity ringdown diagnostic for atmospheric particulate matter

Abstract

A nonresonant cavity ringdown diagnostic to measure light attenuation from atmospheric particulate matter at 532- and 355-nm wavelengths is described. The presence of atmospheric particulate is clearly detectable with this technique, as demonstrated by experimental results. The extinction cross section is higher at 355 than at 532 nm, although we were able to purchase significantly higher-reflectivity optics at 532 nm. The expected advantage at 355 nm is thus lost. This new technique is compared with a commercially available instrument, and sensitivity limitations are discussed.

Measurement of aerosol optical extinction using diode laser cavity ringdown spectroscopy

“…At an integration time of 10 s, both channels can achieve the standard deviation precision of 0.24 Mm −1 (1σ). This detection limit is similar to those achieved in other CRDS instruments using pulsed lasers and modulated diode lasers [3,8,9,28]. The ambient measurement signals, however, were noisier due to the fluctuations from wind, temperature, pressure (not maintained at a constant in our setup), etc.…”

“…In particular, in situ measurements of the extinction and other optical parameters of atmospheric aerosols are crucial, and these require real-time, accurate, and sensitive techniques that can detect the ambient aerosols and their rapid temporal and spatial changes. Recent years have seen a rapid rise in the use of cavity ringdown spectroscopy (CRDS), a sensitive and direct optical extinction technique, to determine the optical properties of both laboratory generated and atmospheric ambient aerosols [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17].…”

“…Sappey et al [3] and Smith and Atkinson [4] were among the first research groups to apply CRDS in aerosol extinction measurements and quantify the extinction of the ambient atmospheric particles. Many more studies have been subsequently carried out to measure the optical extinction of aerosol particles using CRDS [6][7][8][9][10].…”

Sources of Error and Uncertainty in the Use of Cavity Ring Down Spectroscopy to Measure Aerosol Optical Properties

“…A-CRDS is now routinely used in laboratory (Sappey et al 1998;Vander Wal and Ticich 1999;Smith and Atkinson 2001;Bulatov et al 2002Bulatov et al , 2003Bulatov et al , 2006Strawa et al 2003;Pettersson et al 2004;Baynard et al 2006;Garland et al 2007;Riziq et al 2007;Rudić et al 2007;Dinar et al 2008;Riziq et al 2008;Butler et al 2009;Freedman et al 2009;Khalizov et al 2009;Lang-Yona et al 2009Radney et al 2009;Xue et al 2009;Adler et al 2010;Hasenkopf et al 2010;Miles et al 2010aMiles et al , 2010b and field studies (Thompson et al 2002(Thompson et al , 2003Strawa et al 2006;Garland et al 2008;Nakayama et al 2010) to measure extinction by both aerosol ensembles (Vander Wal and Ticich 1999;Thompson et al 2002Thompson et al , 2003Thompson et al , 2008Strawa et al 2003;Pettersson et al 2004;Baynard et al 2006Baynard et al , 2007Garland et al 2007;Riziq et al 2007;Beaver et al 2008;…”

Cavity Ring-Down and Cavity-Enhanced Detection Techniques for the Measurement of Aerosol Extinction

“…It has been noticed early on that ambient aerosol can contribute significantly to the CRD signal (Ramponi et al 1988), but CRD systems have been used only recently to monitor aerosols (Sappey et al 1998) and their extinction (Smith and Atkinson 2001;Strawa et al 2002;Thompson et al 2002). In the following, we discuss a unique hybrid CRD/CED system based on a passively Q-switched Nd:YAG laser for the measurement of aerosol extinction with a large dynamic range.…”