Use of Broadband, Continuous-Wave Diode Lasers in Cavity Ring-Down Spectroscopy for Liquid Samples

Hallock, Alexander J.; Berman, Elena S. F.; Zare, Richard N.

doi:10.1366/000370203321666614

Cited by 23 publications

(25 citation statements)

References 12 publications

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“…It should be pointed out that a min is directly proportional to the base path length, and at 20 cm, the base path length used in this study, is amongst the longest used to date. It is most similar to those used in previous studies by Hallock et al 9,10 and it is with these studies that closest comparison should be made. The first study by Hallock et al 9 made CRDS measurements in a 21 cm base path length cell.…”

Section: Discussionsupporting

confidence: 66%

“…Hallock et al 9 state that LODs of 10 pM could be achieved with their experimental setup for strong absorbers with molar extinction coefficients of 1 Â 10 5 M À1 cm À1 but no actual measurements on suitable analytes were reported. The second Hallock et al study 10 did not report an LOD for their kinetic measurements on methylene blue, whilst the other studies in Table 2 have much higher reported LODs as a result of much shorter base path lengths.…”

Section: Discussionmentioning

confidence: 91%

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Liquid-phase broadband cavity enhanced absorption spectroscopy (BBCEAS) studies in a 20 cm cell

Seetohul

Ali

Islam

2009

Analyst

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Sensitive liquid-phase measurements have been made in a 20 cm cell using broadband cavity enhanced absorption spectroscopy (BBCEAS). The cavity was formed by two high reflectivity mirrors which were in direct contact with the liquid-phase analytes. Careful choice of solvent was required to minimise the effect of background solvent absorptions. Measurements were made on the broad absorber Sudan black, dissolved in acetonitrile, using a white LED light source and R $ 0.99 cavity mirrors, leading to a cavity enhancement factor (CEF) of 82 at 584 nm. The sensitivity as measured by the minimum detectable change in the absorption coefficient (a min ) was 3.4 Â 10 À7 cm À1 . Further measurements were made on the strong absorber methylene blue dissolved in acetonitrile at 655 nm. A white LED was used with the R $ 0.99 cavity mirrors, leading to a CEF of 78 and a min ¼ 4.4 Â 10 À7 cm À1 . The use of a more intense red LED also allowed measurements with higher reflectivity R $ 0.999 cavity mirrors, leading to a CEF of 429 and a min ¼ 2.8 Â 10 À7 cm À1 . The sensitivity was limited by dark noise from the detector but nevertheless appears to represent the most sensitive liquid-phase absorption measurement to date.

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Section: Discussionsupporting

confidence: 66%

Section: Discussionmentioning

confidence: 91%

Liquid-phase broadband cavity enhanced absorption spectroscopy (BBCEAS) studies in a 20 cm cell

Seetohul

Ali

Islam

2009

Analyst

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“…The signal-to-noise ratio was comparable to the Brewster's-angle cuvette approach mentioned above (1,69). In subsequent studies, the repetition rate of the system was increased from 10 Hz (1) to 10 kHz using a CW-CRDS approach (71,72). Whereas one may expect a signal-to-noise ratio improvement of a factor of 30 (from the 1000-fold increase of the repetition rate), the investigators obtained only a threefold increase.…”

Section: Liquid-phase Cavity Ring-down Spectroscopy Measurementsmentioning

confidence: 72%

“…As mentioned above, intracavity surfaces can be circumvented by filling the entire cavity with liquid (1,71,72). Importantly, early studies using a liquid-filled cavity revealed that the mirror reflectivities did not exhibit degradation when in contact with the liquid and that neither stirring nor applying a continuous flow posed a disadvantage.…”

Section: Liquid-phase Cavity Ring-down Spectroscopy Measurementsmentioning

confidence: 99%

“…Whereas one may expect a signal-to-noise ratio improvement of a factor of 30 (from the 1000-fold increase of the repetition rate), the investigators obtained only a threefold increase. This modest increase may be due to signal averaging prior to fitting: Because the speed of data transfer and handling is commonly limited to several kilohertz, traces must be averaged on the read-out system prior to data transfer and handling (1,71,72), which results in loss of information.…”

Section: Liquid-phase Cavity Ring-down Spectroscopy Measurementsmentioning

confidence: 99%

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Liquid-Phase and Evanescent-Wave Cavity Ring-Down Spectroscopy in Analytical Chemistry

Sneppen

Ariese

Gooijer

et al. 2009

Annual Rev. Anal. Chem.

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Due to its simplicity, versatility, and straightforward interpretation into absolute concentrations, molecular absorbance detection is widely used in liquidphase analytical chemistry. Because this method is inherently less sensitive than zero-background techniques such as fluorescence detection, alternative, more sensitive measurement principles are being explored. This review discusses one of these: cavity ring-down spectroscopy (CRDS). Advantages of this technique include its long measurement pathlength and its insensitivity to light-source-intensity fluctuations. CRDS is already a wellestablished technique in the gas phase, so we focus on two new modes: liquidphase CRDS and evanescent-wave (EW)-CRDS. Applications of liquidphase CRDS in analytical chemistry focus on improving the sensitivity of absorbance detection in liquid chromatography. Currently, EW-CRDS is still in early stages: It is used to study basic interactions between molecules and silica surfaces. However, in the future this method may be used to develop, for instance, biosensors with high specificity.

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Cavity Ringdown Laser Absorption Spectroscopy

Wang

Miller

Winstead

2008

Encyclopedia of Analytical Chemistry

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Cavity ringdown spectroscopy (CRDS) has developed rapidly during the last two decades and has been implemented for a variety of applications ranging from fundamental spectroscopic studies, trace chemical detection for environmental monitoring, combustion flame chemistry and plasma diagnostics, elemental and isotopic measurements, breath gas analysis, and fiber ringdown chemical and physical sensor development. A host of chemical species, including atoms, ions, molecules, clusters, and free radicals, have been studied by CRDS. The experimental ringdown scheme has also evolved from an original mirror‐based format to various new forms for detection and analysis of analytes in either gas phase or liquid solutions. Recent research effort has also extended the CRDS approach for fiber optical sensor development. CRDS has become a mature spectrometric technique for a range of prototype and commercial instrumentation. This article provides a review of the latest developments in CRDS applications, specifically emphasizing new trends in elemental and isotopic analysis, plasma diagnostics, breath gas analysis, and new fiber ringdown techniques for sensor development. The introduction of cutting‐edge laser sources into CRDS methods, the combination of CRDS with conventional analytical tools, and current CRDS instrumentation are also briefly discussed.

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Use of Broadband, Continuous-Wave Diode Lasers in Cavity Ring-Down Spectroscopy for Liquid Samples

Cited by 23 publications

References 12 publications

Liquid-phase broadband cavity enhanced absorption spectroscopy (BBCEAS) studies in a 20 cm cell

Liquid-phase broadband cavity enhanced absorption spectroscopy (BBCEAS) studies in a 20 cm cell

Liquid-Phase and Evanescent-Wave Cavity Ring-Down Spectroscopy in Analytical Chemistry

Cavity Ringdown Laser Absorption Spectroscopy

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