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Mukhopadhyay D, Bandyopadhyay M, Tyagi H, Patel K. Advancement of Langmuir probe-based laser photo-detachment technique for negative ion density measurement in a high-power helicon plasma source. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2024; 95:043006. [PMID: 38683055 DOI: 10.1063/5.0186429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Accepted: 03/30/2024] [Indexed: 05/01/2024]
Abstract
In the pursuit of precise diagnostics for measuring negative ion density in a helicon plasma source (HPS), a new approach utilizing a radio frequency (RF) broadband transformer-based Langmuir probe is developed specifically for laser photo-detachment (LPD) analysis. This inductively coupled LPD technique is useful for high power RF systems in which capacitive RF noise is in the same scale as the pulsed photo-detachment signal. The signal acquired by this transformer-based probe is compared against the conventional Langmuir probe-based LPD technique, revealing a remarkable enhancement in signal fidelity through an improved signal-to-noise ratio (SNR) achieved by the RF broadband transformer methodology. In addition, the localized hydrogen negative ion density measurements obtained through this probe are harmoniously aligned with the line-averaged negative ion density derived from the cavity ringdown spectroscopy (CRDS) technique. These concurrence measurements highlight the RF broadband transformer-based approach's accuracy in capturing localized negative ion density during helicon mode operation in an HPS setup. Furthermore, the correlation of negative ion density values with RF input exhibits a consistent trend in tandem with background plasma density. Notably, both CRDS and LPD measurements ascertain negative ion densities ranging from ∼5 to 6×1016 m-3 under an RF power of 500-700 W and a pressure of 8 × 10-3 mbar, all under the influence of a 55 G axial magnetic field. These specific parameters represent the optimal operational configuration for effective negative ion production with the present experimental HPS setup. Due to its better SNR, the RF broadband transformer-based Langmuir probe emerges as a useful tool for LPD diagnostics, particularly in the presence of pervasive RF noise.
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Affiliation(s)
- D Mukhopadhyay
- Institute for Plasma Research, Bhat, Gandhinagar 382428, Gujarat, India
- Homi Bhabha National Institute (HBNI), Anushaktinagar, Mumbai 400094, Maharashtra, India
| | - M Bandyopadhyay
- Institute for Plasma Research, Bhat, Gandhinagar 382428, Gujarat, India
- Homi Bhabha National Institute (HBNI), Anushaktinagar, Mumbai 400094, Maharashtra, India
- ITER-India Institute for Plasma Research, Bhat, Gandhinagar 382428, Gujarat, India
| | - H Tyagi
- ITER-India Institute for Plasma Research, Bhat, Gandhinagar 382428, Gujarat, India
| | - K Patel
- Institute for Plasma Research, Bhat, Gandhinagar 382428, Gujarat, India
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Alnaanah SA, Roussel TJ, Ghithan JH, Qatamin AH, Irziqat MA, Telfah H, Liu J, Mendes SB. Electroactive Interface for Enabling Spectroelectrochemical Investigations in Evanescent-Wave Cavity-Ring-Down Spectroscopy. Anal Chem 2020; 92:11288-11296. [PMID: 32689790 DOI: 10.1021/acs.analchem.0c01956] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In this study, we report the development of an electrically active solid-liquid interface for the evanescent-wave cavity-ring-down spectroscopic (EW-CRDS) technique to enable spectroelectrochemical investigations of redox events. Because of a high-quality transparent conductive electrode film of indium tin oxide (ITO) coated on the interface of total internal reflection of the EW-CRDS platform, a cavity ring-down time of about 900 ns was obtained allowing spectroelectrochemical studies at solid-liquid interfaces. As a proof-of-concept on the capabilities of the developed platform, measurements were performed to address the effects of an applied electric potential to the adsorption behavior of the redox protein cytochrome c (Cyt-C) onto different interfaces, namely, bare-ITO, 3-aminopropyl triethoxysilane (APTES), and Cyt-C antibody. For each interface, the adsorption and desorption constants, the surface equilibrium constant, the Gibbs free energy of adsorption, and the surface coverage were optically measured by our electrically active EW-CRDS tool. Optical measurements at a set of constant discrete values of the applied electric potential were acquired for kinetic adsorption analysis. Cyclic voltammetry (CV) scans under synchronous optical readout were performed to study the effects of each molecular interface on the redox process of surface-adsorbed protein species. Overall, the experimental results demonstrate the ability of the electro-active EW-CRDS platform to unambiguously measure electrode-driven redox events of surface-confined molecular species at low submonolayer coverages and at a single diffraction-limited spot. Such capability is expected to open several opportunities for the EW-CRDS technique to investigate a variety of electrochemical phenomena at solid-liquid interfaces.
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Affiliation(s)
- Shadi A Alnaanah
- Department of Physics and Astronomy, University of Louisville, Louisville, Kentucky 40208, United States
| | - Thomas J Roussel
- Department of Bioengineering, University of Louisville, Louisville, Kentucky 40208, United States
| | - Jafar H Ghithan
- Department of Physics and Astronomy, University of Louisville, Louisville, Kentucky 40208, United States
| | - Aymen H Qatamin
- Department of Physics and Astronomy, University of Louisville, Louisville, Kentucky 40208, United States
| | - Mohammed A Irziqat
- Department of Physics and Astronomy, University of Louisville, Louisville, Kentucky 40208, United States
| | - Hamzeh Telfah
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, United States
| | - Jinjun Liu
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, United States
| | - Sergio B Mendes
- Department of Physics and Astronomy, University of Louisville, Louisville, Kentucky 40208, United States
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Lehmann KK. Resonance enhanced two-photon cavity ring-down spectroscopy of vibrational overtone bands: A proposal. J Chem Phys 2019; 151:144201. [DOI: 10.1063/1.5122988] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Affiliation(s)
- Kevin K. Lehmann
- Departments of Chemistry and Physics, University of Virginia, Charlottesville, Virginia 22904-4319, USA
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Mukhopadhyay D, Pandey A, Bandyopadhyay M, Tyagi H, Yadav R, Chakraborty A. Quantification of atomic hydrogen anion density in a permanent magnet based helicon ion source (HELEN) by using pulsed ring down spectroscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2019; 90:083103. [PMID: 31472659 DOI: 10.1063/1.5093914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 07/16/2019] [Indexed: 06/10/2023]
Abstract
In the present work, a permanent magnet-based helicon plasma source (HELEN) is characterized as a negative ion source. A noninvasive diagnostic technique based on cavity ring down spectroscopy (CRDS) is developed to measure the line-integrated negative hydrogen ion (H-) density in HELEN. This paper discusses the experimental results in which negative hydrogen ion density is measured for different magnetic field, pressure, and RF (13.56 MHz) power configurations. It is observed that in high power range (800-850 W), the source is operating in helicon wave heating mode with a background plasma density of ∼1018 m-3 and electron temperature of ∼2 eV. Negative hydrogen ion density is measured by CRDS method and also by optical emission spectroscopic technique. The measured negative ion density is in the range of ∼1016 m-3 under volume mode operational condition even without any use of standard magnetic filter or cesium seeding in the downstream region. The influence of pressure variation (pressure range from 4 × 10-3 mbar to 4 × 10-2 mbar) on negative ion density production is not significant, except for a particular axial magnetic field configuration (55 G) and at 8 × 10-3 mbar pressure, where ∼34% hike is observed.
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Affiliation(s)
- D Mukhopadhyay
- Institute for Plasma Research, Bhat, Gandhinagar 382428, Gujarat, India
| | - A Pandey
- Institute for Plasma Research, Bhat, Gandhinagar 382428, Gujarat, India
| | - M Bandyopadhyay
- Institute for Plasma Research, Bhat, Gandhinagar 382428, Gujarat, India
| | - H Tyagi
- ITER-India, Institute for Plasma Research, Bhat, Gandhinagar 382428, Gujarat, India
| | - R Yadav
- ITER-India, Institute for Plasma Research, Bhat, Gandhinagar 382428, Gujarat, India
| | - A Chakraborty
- Institute for Plasma Research, Bhat, Gandhinagar 382428, Gujarat, India
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Yao YJ, Lin KC. DNA interaction probed by evanescent wave cavity ring-down absorption spectroscopy via functionalized gold nanoparticles. Anal Chim Acta 2014; 820:1-8. [DOI: 10.1016/j.aca.2014.01.045] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Revised: 01/20/2014] [Accepted: 01/24/2014] [Indexed: 01/05/2023]
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Interaction between crystal violet and anionic surfactants at silica/water interface using evanescent wave-cavity ring-down absorption spectroscopy. J Colloid Interface Sci 2012; 379:41-7. [DOI: 10.1016/j.jcis.2012.04.041] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Revised: 04/13/2012] [Accepted: 04/16/2012] [Indexed: 11/22/2022]
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O'Connell MA, de Cuendias A, Gayet F, Shirley IM, Mackenzie SR, Haddleton DM, Unwin PR. Evanescent wave cavity ring-down spectroscopy (EW-CRDS) as a probe of macromolecule adsorption kinetics at functionalized interfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:6902-6910. [PMID: 22489550 DOI: 10.1021/la3006053] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Evanescent wave cavity ring-down spectroscopy (EW-CRDS) has been employed to study the interfacial adsorption kinetics of coumarin-tagged macromolecules onto a range of functionalized planar surfaces. Such studies are valuable in designing polymers for complex systems where the degree of interaction between the polymer and surface needs to be tailored. Three tagged synthetic polymers with different functionalities are examined: poly(acrylic acid) (PAA), poly(3-sulfopropyl methacrylate, potassium salt) (PSPMA), and a mannose-modified glycopolymer. Adsorption transients at the silica/water interface are found to be characteristic for each polymer, and kinetics are deduced from the initial rates. The chemistry of the adsorption interfaces has been varied by, first, manipulation of silica surface chemistry via the bulk pH, followed by surfaces modified by poly(L-glutamic acid) (PGA) and cellulose, giving five chemically different surfaces. Complementary atomic force microscopy (AFM) imaging has been used for additional surface characterization of adsorbed layers and functionalized interfaces to allow adsorption rates to be interpreted more fully. Adsorption rates for PSPMA and the glycopolymer are seen to be highly surface sensitive, with significantly higher rates on cellulose-modified surfaces, whereas PAA shows a much smaller rate dependence on the nature of the adsorption surface.
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Powell HV, O’Connell MA, Zhang M, Mackenzie SR, Unwin PR. Evanescent Wave Cavity Ringdown Spectroscopy: A Platform for the Study of Supported Lipid Bilayers. Anal Chem 2012; 84:2585-91. [DOI: 10.1021/ac203493p] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Hayley V. Powell
- Department
of Chemistry, University of Warwick, Coventry
CV4 7AL, United Kingdom
| | - Michael A. O’Connell
- Department
of Chemistry, University of Warwick, Coventry
CV4 7AL, United Kingdom
| | - Meiqin Zhang
- Department
of Chemistry, University of Warwick, Coventry
CV4 7AL, United Kingdom
| | - Stuart R. Mackenzie
- Department of Chemistry, University of Oxford, Physical and Theoretical Chemistry Laboratory, Oxford OX1 3QZ,
United Kingdom
| | - Patrick R. Unwin
- Department
of Chemistry, University of Warwick, Coventry
CV4 7AL, United Kingdom
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Mantha JH, Ismail AI, Cline JI. Polarized normal-incidence cavity ring-down spectroscopy: probing spiropyran photochromism in thin PMMA films and toluene. J Phys Chem A 2011; 115:410-8. [PMID: 21210692 DOI: 10.1021/jp105474c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A normal-incidence geometry, polarization-resolved cavity ring-down spectroscopy technique (polarized NICRDS) is described to probe the polarized absorbance of surface-adsorbed thin films and short-path length liquid samples. The technique is demonstrated by a kinetic study of the photochromic behavior of the spiropyran dye 6,8-dibromo-1', 3'-dihydro-1', 3', 3'-trimethylspiro[2H-1-benzopyran-2, 2'-(2H)-indole]. The technique is shown potentially to have monolayer coverage sensitivity and can measure the angular orientation distribution of analyte molecules. The photochromic kinetics of 6,8-dibromoBIPS in toluene solution were qualitatively consistent with a previous study of this molecule using conventional absorption spectroscopy. The absorption polarizations and slow ring-closing kinetics measured in a thin poly(methyl methacrylate) film are consistent with a strong interaction of the spiropyran and merocyanine forms with the polymer matrix.
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Affiliation(s)
- Jordan H Mantha
- Department of Chemistry, University of Nevada, Reno, Nevada 89557-0216, USA
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Schnippering M, Neil SRT, Mackenzie SR, Unwin PR. Evanescent wave cavity-based spectroscopic techniques as probes of interfacial processes. Chem Soc Rev 2011; 40:207-20. [DOI: 10.1039/c0cs00017e] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Powell HV, Schnippering M, Cheung M, Macpherson JV, Mackenzie SR, Stavros VG, Unwin PR. Probing Redox Reactions of Immobilized Cytochrome c Using Evanescent Wave Cavity Ring-Down Spectroscopy in a Thin-Layer Electrochemical Cell. Chemphyschem 2010; 11:2985-91. [DOI: 10.1002/cphc.201000213] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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12
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A free-flowing soap film combined with cavity ring-down spectroscopy as a detection system for liquid chromatography. J Chromatogr A 2010; 1217:3316-20. [DOI: 10.1016/j.chroma.2009.10.053] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2009] [Revised: 10/13/2009] [Accepted: 10/16/2009] [Indexed: 11/19/2022]
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13
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Neil SR, Maeda K, Henbest KB, Goez M, Hemmens R, Timmel CR, Mackenzie SR. Cavity enhanced detection methods for probing the dynamics of spin correlated radical pairs in solution. Mol Phys 2010. [DOI: 10.1080/00268971003614368] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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14
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Zhang M, Powell HV, Mackenzie SR, Unwin PR. Kinetics of porphyrin adsorption and DNA-assisted desorption at the silica-water interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:4004-4012. [PMID: 20104901 DOI: 10.1021/la903438p] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Evanescent wave cavity ring-down spectroscopy (EW-CRDS) has been used to study in situ the kinetics of the adsorption of 5,10,15,20-tetrakis(4-N-methylpyridiniumyl)porphyrin (TMPyP) from pH 7.4 phosphate buffer solution (PBS) to the silica-water interface and the interaction of calf thymus DNA (CT-DNA) with the resulting TMPyP-functionalized surface. TMPyP was delivered to the silica surface using an impinging jet technique to allow relatively fast surface kinetics to be accessed. Adsorption was first-order in TMPyP, and the initial adsorption rate constant at the bare surface was found to be k = (4.1 +/- 0.6) x 10(-2) cm s(-1). A deceleration in the adsorption kinetics was observed at longer times that could be described semiquantitatively using an Elovich-type kinetic expression. The limiting value of the absorbance corresponded approximately to monolayer coverage (6.2 x 10(13) molecules cm(-2)). Exposure of the TMPyP-modified silica surface to CT-DNA, achieved by flowing CT-DNA solution over the functionalized surface, resulted in efficient desorption of the TMPyP. The desorption process was driven by the interaction of TMPyP with CT-DNA, which UV-vis spectroscopy indicated involved intercalative binding. The desorption kinetics were also simulated using complementary finite element modeling of convection-diffusion coupled to a surface process.
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Affiliation(s)
- Meiqin Zhang
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
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Egashira K, Terasaki A, Kondow T. Photon-trap spectroscopy applied to molecules adsorbed on a solid surface: probing with a standing wave versus a propagating wave. APPLIED OPTICS 2010; 49:1151-1157. [PMID: 20197812 DOI: 10.1364/ao.49.001151] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We apply photon-trap spectroscopy, a generalized scheme of cavity ringdown spectroscopy, to infrared spectroscopy of molecular adsorbates on a solid substrate. The storage lifetime of light in a high-finesse Fabry-Perot cavity provides a high absorbance sensitivity for the substrate sample, which is placed exactly normal to the light beam in the cavity to minimize optical losses. Infrared spectra of the C-H stretching vibration of alkylsiloxane monolayer films on a silicon substrate are measured in three ways, namely by employing pulsed and continuous-wave lasers as well as by conventional Fourier transform infrared spectroscopy. The magnitude of optical absorption is shown to vary by the character of the interacting light used in the measurement, i.e., a standing wave versus a propagating wave.
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Affiliation(s)
- Kazuhiro Egashira
- East Tokyo Laboratory, Genesis Research Institute, Inc., 717-86 Futamata, Ichikawa, Chiba 272-0001, Japan
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Chen MS, Fan HF, Lin KC. Kinetic and Thermodynamic Investigation of Rhodamine B Adsorption at Solid/Solvent Interfaces by Use of Evanescent-Wave Cavity Ring-Down Spectroscopy. Anal Chem 2009; 82:868-77. [DOI: 10.1021/ac9020209] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ming-Shiang Chen
- Department of Chemistry, National Taiwan University, Taipei 106, and Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan
| | - Hsiu-Fang Fan
- Department of Chemistry, National Taiwan University, Taipei 106, and Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan
| | - King-Chuen Lin
- Department of Chemistry, National Taiwan University, Taipei 106, and Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan
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Powell HV, Schnippering M, Mazurenka M, Macpherson JV, Mackenzie SR, Unwin PR. Evanescent wave cavity ring-down spectroscopy as a probe of interfacial adsorption: interaction of Tris(2,2'-bipyridine)ruthenium(II) with silica surfaces and polyelectrolyte films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:248-255. [PMID: 19072204 DOI: 10.1021/la802707q] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Evanescent wave cavity ring-down spectroscopy (EW-CRDS) has been used to study the interaction of the tris(2,2'-bipyridine)ruthenium(II) complex, [Ru(bpy)(3)](2+), at both native silica surfaces and surfaces modified with polyelectrolyte films. Both poly-l-lysine (PLL) and PLL/poly-l-glutamic acid (PGA) bilayer functionalized interfaces have been studied. Concentration isotherms exhibit Langmuir-type adsorption behavior on both silica and PGA-terminated surfaces from which equilibrium constants have been derived. The pH-dependence of the [Ru(bpy)(3)](2+) adsorption to silica and the PLL/PGA film has also been investigated. For the latter substrate, the effective surface pK(a) of the acid groups was found to be 5.5. The effect of supporting electrolyte was also investigated and was shown to have a significant effect on the extent of [Ru(bpy)(3)](2+) adsorption. A thin-layer electrochemical cell arrangement, in which a working electrode was positioned just above the substrate, was used to change the solution pH in a controlled way via the potential-pulsed chronoamperometric oxidation of water. By measuring the optical absorption using EW-CRDS during such experiments, the desorption of [Ru(bpy)(3)](2+) from the surface has been monitored in real time. Experiments were carried out at different cell thicknesses and at various pulse durations. By combining data from the EW-CRDS experiments with fluorescence confocal laser scanning microscopy (CLSM) to determine the pH at the substrate surface, the pK(a) of the PLL/PGA film could be ascertained and was found to agree with the static pH isotherm measurements. These studies provide a platform for the further use of electrochemistry combined with EW-CRDS to investigate dynamic processes at interfaces.
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Affiliation(s)
- Hayley V Powell
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL
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18
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Evanescent wave broadband cavity enhanced absorption spectroscopy using supercontinuum radiation: A new probe of electrochemical processes. Electrochem commun 2008. [DOI: 10.1016/j.elecom.2008.09.014] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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19
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Wang X, Hinz M, Vogelsang M, Welsch T, Kaufmann D, Jones H. A new approach to detecting biologically active substances with evanescent-wave cavity ring-down spectroscopy. Chem Phys Lett 2008. [DOI: 10.1016/j.cplett.2008.10.086] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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van der Sneppen L, Buijs JB, Gooijer C, Ubachs W, Ariese F. Evanescent-wave cavity ring-down spectroscopy for enhanced detection of surface binding under flow injection analysis conditions. APPLIED SPECTROSCOPY 2008; 62:649-654. [PMID: 18559152 DOI: 10.1366/000370208784657977] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The feasibility of liquid-phase evanescent-wave cavity ring-down spectroscopy (EW-CRDS) for surface-binding studies under flow-injection analysis (FIA) conditions is demonstrated. The EW-CRDS setup consists of an anti-reflection coated Dove prism inside a linear cavity (with standard or super-polishing of the total internal reflective (TIR) surface). A teflon spacer with an elliptical hole clamped on this surface acts as a 20 muL sized flow cell. The baseline noise of this system is of the order of 10(-4) absorbance units; the baseline remains stable over a prolonged time and the prism surface does not become contaminated during repeated injections of the reversibly adsorbing test dyes Crystal Violet (CV) and Direct Red 10 (DR10). At typical FIA or liquid chromatography (LC) flow rates, the system has sufficient specificity to discriminate between species with different surface affinities. For CV a much stronger decrease in ring-down time is observed than calculated based on its bulk concentration and the effective depth probed by the evanescent wave, indicating binding of this positively charged dye to the negatively charged prism surface. The amount of adsorption can be influenced by adjusting the flow rate or the eluent composition. At a flow rate of 0.5 mL/min, an enrichment factor of 60 was calculated for CV; for the poorly adsorbing dye DR10 it is 5. Super-polishing of the already polished TIR surface works counter-productively. The adsorbing dye Crystal Violet has a detection limit of 3 muM for the standard polished surface; less binding occurs on the super-polished surface and the detection limit is 5 muM. Possible applications of EW-CRDS for studying surface binding or the development of bio-assays are discussed.
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Affiliation(s)
- L van der Sneppen
- Laser Centre, Vrije Universiteit, De Boelelaan 1081-1083, 1081 HV Amsterdam, The Netherlands
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21
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Ruth AA, Lynch KT. Incoherent broadband cavity-enhanced total internal reflection spectroscopy of surface-adsorbed metallo-porphyrins. Phys Chem Chem Phys 2008; 10:7098-108. [DOI: 10.1039/b809591d] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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22
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Fisk JD, Batten R, Jones G, O'Reilly JP, Shaw AM. pH dependence of the crystal violet adsorption isotherm at the silica-water interface. J Phys Chem B 2007; 109:14475-80. [PMID: 16852824 DOI: 10.1021/jp051211z] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The pH-dependent adsorption isotherms for the charged chromophore crystal violet, CV(+), have been measured with three different bases by a free-running cavity implementation of evanescent wave cavity ring-down spectroscopy. The ratio of the maximal absorbance measurements at pH 5.10 and 9.05 is consistent with a Q2:Q3 silanol site ratio of 72.8:27.2. The adsorption isotherms have been interpreted in terms a cooperative binding adsorption allowing more than one ionic species to bind to each silanol group. The surface concentration is consistent with a silanol charge density of 1.92 +/- 0.55 nm(-2) and a total neutralized interface layer structure extending 9 nm from the surface. Binding constants and stoichiometric coefficients are derived for CV(+) to both the Q2 and Q3 sites. A variation of the adsorption isotherm with base is observed so that the isotherm at pH 9.05 adjusted with ammonium hydroxide sets up a competitive acid-base equilibrium with the SiOH groups with only 49% of the surface silanol sites dissociated. The implications for functionalized surfaces in chromatography are discussed.
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Affiliation(s)
- Jonathan D Fisk
- School of Biological and Chemical Sciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
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Antonietti JM, Michalski M, Heiz U, Jones H, Lim KH, Rösch N, Vitto AD, Pacchioni G. Optical absorption spectrum of gold atoms deposited on SiO(2) from cavity ringdown spectroscopy. PHYSICAL REVIEW LETTERS 2005; 94:213402. [PMID: 16090321 DOI: 10.1103/physrevlett.94.213402] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2005] [Indexed: 05/03/2023]
Abstract
The optical properties of gold atoms supported on amorphous silica (alpha-SiO2) were studied experimentally and theoretically in the visible range. Samples were prepared in situ by depositing Au atoms at low coverages (5 x 10(12) cm(-2)) in UHV, and the optical absorption spectra were recorded by cavity ringdown spectroscopy. The atomic absorption bands can be attributed to gold atoms trapped at [triple bond] Si-O(.-) and [triple bond]Si-O(-) defect sites. The absence of optical transitions typical for Au(2) shows that the atoms are efficiently anchored at these defect sites, preventing diffusion and aggregation. Furthermore, these experimental results reveal that it is now possible to study optical properties of well-defined nanostructures at surface coverages as low as 5 x 10(11) cm(-2).
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Affiliation(s)
- Jean-Marie Antonietti
- Lehrstuhl für Physikalische Chemie 1, Technische Universität München, D-85747 Garching, Germany.
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24
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Martin WB, Mirov S, Martyshkin D, Venugopalan R, Shaw AM. Hemoglobin adsorption isotherm at the silica-water interface with evanescent wave cavity ring-down spectroscopy. JOURNAL OF BIOMEDICAL OPTICS 2005; 10:024025. [PMID: 15910098 DOI: 10.1117/1.1891368] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Evanescent wave cavity ring-down spectroscopy (EW-CRDS) is used to observe the adsorption isotherm for hemoglobin (Hb) from controlled urine samples to assess the potential for rapid diagnosis in hemoglobinuria. The absorbance of Hb at 425 nm is monitored using an alexandrite laser-pumped, room temperature, LiF:F2+** color-center pulsed laser. A minimum absorbance detection level of 2.57 x 10(-4) is achieved, corresponding to a minimum detectable concentration of Hb in urea of 5.8 nM. A multilayered Hb biofilm is formed, and a minimum of eight layers are required to model the adsorption isotherm, allowing for cooperative binding within the layers and extending 56 nm into the interface. A binding constant for Hb to silica 18.23+/-7.58 x 10(6) M is derived, and a binding constant for Hb to Hb in subsequent layers is determined to be 5.631+/-0.432 x 10(5) M. Stoichiometric binding coefficients of 1.530+/-0.981 for layer one and 1.792+/-0.162 for subsequent layers suggest that cooperative binding both to the silica surface and between the layers of the biofilm is important.
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Affiliation(s)
- W Blake Martin
- University of Alabama at Birmingham, Department of Biomedical Engineering, 1075 13th Street South, Suite 370, Birmingham, Alabama 35294-4440, USA.
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25
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Li F, Zare RN. Molecular Orientation Study of Methylene Blue at an Air/Fused-Silica Interface Using Evanescent-Wave Cavity Ring-Down Spectroscopy. J Phys Chem B 2005; 109:3330-3. [PMID: 16851361 DOI: 10.1021/jp045290a] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Using evanescent-wave cavity ring-down spectroscopy (EW-CRDS), we monitored the change in the absorbance of a thin film of methylene blue (MB) at an air/fused-silica interface while varying the polarization of the incident light (600 nm). We derived the average orientation angle of the planar MB molecules with respect to the surface normal and observed that the average orientation angle decreases as the surface concentration increases. At low surface concentrations, the MB molecules lie almost flat on the surface, whereas at higher surface concentrations the molecules become vertically oriented.
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Affiliation(s)
- Fuping Li
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
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26
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Abstract
An exploratory study on a novel fiber ringdown pressure sensor is presented. With this technique, pressure measurements are achieved in a time domain by measurement of ringdown times. The proof-of-concept device consists of a diode laser light source, two 2 x 1 fiber couplers, a section of fused-silica single-mode fiber, a photodetector, and an electronic control. The sensor's performance in the areas of stability, repeatability, and dynamic range is explored. The results demonstrate the new concept of fiber pressure sensors and the technical feasibility of developing a new generation of fiber sensors for pressure measurements.
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Affiliation(s)
- Chuji Wang
- Diagnostic Instrumentation and Analysis Laboratory, Mississippi State University, 205 Research Boulevard, Starkville, Mississippi 39759, USA.
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28
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Pipino ACR, Hoefnagels JPM, Watanabe N. Absolute surface coverage measurement using a vibrational overtone. J Chem Phys 2004; 120:2879-88. [PMID: 15268435 DOI: 10.1063/1.1637338] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Determination of absolute surface coverage with sub-monolayer sensitivity is demonstrated using evanescent-wave cavity ring-down spectroscopy (EW-CRDS) and conventional CRDS by employing conservation of the absolute integrated absorption intensity between gas and adsorbed phases. The first C-H stretching overtones of trichloroethylene (TCE), cis-dichloroethylene, and trans-dichloroethylene are probed using the idler of a seeded optical parametric amplifier having a 0.075 cm(-1) line width. Polarized absolute adsorbate spectra are obtained by EW-CRDS using a fused-silica monolithic folded resonator having a finesse of 28 500 at 6050 cm(-1), while absolute absorption cross sections for the gas-phase species are determined by conventional CRDS. A measure of the average transition moment orientation on the surface, which is utilized for the coverage determination, is derived from the polarization anisotropy of the surface spectra. Coverage measurement by EW-CRDS is compared to a mass-spectrometer-based surface-uptake technique, which we also employ for coverage measurements of TCE on thermally grown SiO(2) surfaces. To assess the potential for environmental sensing, we also compare EW-CRDS to optical waveguide techniques developed previously for TCE detection.
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Affiliation(s)
- Andrew C R Pipino
- Chemical Science and Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
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29
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Pipino ACR, Woodward JT, Meuse CW, Silin V. Surface-plasmon-resonance-enhanced cavity ring-down detection. J Chem Phys 2004; 120:1585-93. [PMID: 15268285 DOI: 10.1063/1.1629279] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The cavity ring-down technique is used to probe the absolute optical response of the localized surface plasmon resonance (SPR) of a gold nanoparticle distribution to adsorption of trichloroethylene (TCE) and perchloroethylene (PCE) from the gas phase. Extended Mie theory for a coated sphere with a particle-size-dependent dielectric function is used to elucidate size-dispersion effects, the size-dependence of the SPR sensitivity to adsorption, and the kinetics of adsorption. An approximate Gaussian distribution of nanospheres with a mean diameter of 4.5 nm and a standard deviation of 1.1 nm, as determined by atomic force microscopy, is provided by the intrinsic granularity of an ultrathin, gold film, having a nominal thickness of approximately 0.18 nm. The cavity ring-down measurements employ a linear resonator with an intracavity flow cell, which is formed by a pair of ultrasmooth, fused-silica optical flats at Brewster's angle, where the Au film is present on a single flat. The total system intrinsic loss is dominated by the film extinction, while the angled flats alone contribute only approximately 5 x 10(-5)/flat to the total loss. Based on a relative ring-down time precision of 0.1% for ensembles averages of 25 laser shots from a pulsed optical parametric oscillator, the minimum detectable concentrations of PCE and TCE obtained by probing the SPR response are found to be 2 and 7 x 10(-8) mol/L, respectively, based on a 30 s integration time.
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Affiliation(s)
- Andrew C R Pipino
- Chemical Science and Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
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30
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Evanescent field absorption in a passive optical fiber resonator using continuous-wave cavity ring-down spectroscopy. Chem Phys Lett 2004. [DOI: 10.1016/j.cplett.2003.11.043] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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31
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Shaw AM, Hannon TE, Li F, Zare RN. Adsorption of Crystal Violet to the Silica−Water Interface Monitored by Evanescent Wave Cavity Ring-Down Spectroscopy. J Phys Chem B 2003. [DOI: 10.1021/jp027636s] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Andrew M. Shaw
- School of Chemistry, University of Exeter, Stocker Road, Exeter, EX4 4QD, U.K
| | - Theresa E. Hannon
- Chemistry Department, Stanford University, Stanford, California 94305
| | - Fuping Li
- Chemistry Department, Stanford University, Stanford, California 94305
| | - Richard N. Zare
- Chemistry Department, Stanford University, Stanford, California 94305
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32
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Brown RS, Kozin I, Tong Z, Oleschuk RD, Loock HP. Fiber-loop ring-down spectroscopy. J Chem Phys 2002. [DOI: 10.1063/1.1527893] [Citation(s) in RCA: 104] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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33
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Atkinson DB, Spillman JL. Alkyl Peroxy Radical Kinetics Measured Using Near-infrared CW−Cavity Ring-down Spectroscopy. J Phys Chem A 2002. [DOI: 10.1021/jp0257597] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Dean B. Atkinson
- Department of Chemistry, Portland State University, Portland, Oregon 97207-0751
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Marcus GA, Schwettman HA. Cavity ringdown spectroscopy of thin films in the mid-infrared. APPLIED OPTICS 2002; 41:5167-5171. [PMID: 12206228 DOI: 10.1364/ao.41.005167] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
To demonstrate the potential of the cavity ringdown technique in mid-infrared spectroscopy of thin film samples, we measured absorption losses in a C60 film on a BaF2 substrate using a tunable optical parametric amplifier source. With a Brewster angle sample geometry, we achieved a fractional loss sensitivity as small as 1.3 x 10(-7) with 1.5 cm(-1) resolution, an improvement in sensitivity of 2 orders of magnitude compared to standard Fourier transform infrared methods. At an absorption sensitivity of 5 x 10(-7), spectra of several C60 overtone lines were recorded.
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Affiliation(s)
- George A Marcus
- Department of Physics, Stanford Free Electron Laser Center, Stanford University, California 94305-4085, USA.
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35
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Logunov SL. Cavity ringdown detection of losses in thin films in the telecommunication wavelength window. APPLIED OPTICS 2001; 40:1570-1573. [PMID: 18357150 DOI: 10.1364/ao.40.001570] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The method of cavity ringdown spectroscopy (when a tunable pulsed optical parametric oscillator was used) was extended for the loss evaluation in thin films (2-20-microm thickness). The technique was applied in two key telecommunication wavelength ranges of 1260-1330 and 1480-1650 nm. The measurement sensitivity was determined to be 50 ppm (5 x 10(-5)). The results for polymer films are in close correlation with conventional spectrophotometric data and propagation loss for planar waveguides. Films of greater thickness and better optical quality are expected to provide an even higher loss resolution.
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Affiliation(s)
- S L Logunov
- Science Technology Division, Corning, Incorporated, Sullivan Park, Corning, New York 14831-0000, USA.
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36
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Totschnig G, Baer DS, Wang J, Winter F, Hofbauer H, Hanson RK. Multiplexed continuous-wave diode-laser cavity ringdown measurements of multiple species. APPLIED OPTICS 2000; 39:2009-2016. [PMID: 18345101 DOI: 10.1364/ao.39.002009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Rapid cavity ringdown measurements of multiple broadband absorbing species (methanol and isopropanol) in gas mixtures have been recorded with two multiplexed continuous-wave distributed-feedback diode lasers operating near 1.4 mum. A measurement sensitivity of 2.4 x 10(-9) cm(-1) for a 4.3-s averaging time was achieved in a 39.5-cm-long static cell with 99.94% reflectivity mirrors. This corresponds to a water-vapor detection limit of less than 2 ppb (parts in 10(9)) for the strong H(2)O lines near 1.4 mum. The shot-to-shot noise of the decay time constant tau was approximately 0.3-0.7%, and ringdown acquisition rates as great as 900 Hz were achieved.
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Affiliation(s)
- G Totschnig
- High Temperature Gasdynamics Laboratory, Department of Mechanical Engineering, Stanford University, Stanford, California 94305, USA.
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37
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Pipino AC. Monolithic folded resonator for evanescent wave cavity ringdown spectroscopy. APPLIED OPTICS 2000; 39:1449-1453. [PMID: 18338031 DOI: 10.1364/ao.39.001449] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
An optical resonator is characterized that employs both ultrahigh-reflective coated surfaces and total internal reflection to enable cavity ringdown spectroscopy of surfaces, films, and liquids. The monolithic folded design possesses a polarization-independent finesse that allows polarization-dependent phenomena, such as molecular orientation, to be probed. Although a restricted bandwidth (~15% of the design wavelength) results from use of reflective coatings, the resonator provides high sensitivity and facile operation. A minimum detectable absorption of 2.2 x 10(-6) was obtained for single laser shots by use of multimode excitation at 530 nm with an excimer-pumped, pulsed dye laser.
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38
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Engeln R, von Helden G, van Roij AJA, Meijer G. Cavity ring down spectroscopy on solid C60. J Chem Phys 1999. [DOI: 10.1063/1.477997] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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