Sensitive trace gas detection with cavity enhanced absorption. The authors describe an application of a optical feedback cavity enhanced absorption spectroscopy ofceas for ammonia detection in exhaled breath. This approach enables absorption spectra to be obtained through the integration of the total light signal transmitted through the. A cw distributed feedback quantum cascade laser dfbqcl coupled to a twomirror linear optical cavity has been used to successfully demonstrate opticalfeedback cavity enhanced absorption spectroscopy of ceas at 5.
A new cavity based absorption instrument for detection of. Incoherent broad band cavity enhanced absorption spectroscopy ibbceas, sometimes called broadband cavity enhanced extinction spectroscopy ibbcees, measures the transmission of light intensity through a stable optical cavity consisting of high reflectance mirrors typically r99. Open access publications 51730 freely accessible full text publications. It allows strong cavity transmission, which compensates for low light. Liquidphase analytical applications of uvvisible broadband. Figure 1 is a cartoon of the overall experimental design. With appropriate optical feedback, a distributed feedback dfb diode laser is frequency locked to a vshaped cavity with a free spectral range fsr of 300 mhz and a finesse of 14610. New approaches to cavity enhanced absorption spectroscopy are presented.
Apr 01, 2011 bbceas is a new cavity based absorption technique that uses broadband sources rather than lasers. Linear cavity opticalfeedback cavityenhanced absorption. The instrument utilizes broadband cavity enhanced absorption spectroscopy bbceas and incorporates an optomechanical. Open path incoherent broadband cavityenhanced measurements. Cavity enchanced absorption spectroscopy ceas or integrated. Laser absorption spectrometry las refers to techniques that use lasers to assess the concentration or amount of a species in gas phase by absorption spectrometry as optical spectroscopic techniques in general, and laserbased techniques in particular, have a great potential for detection and monitoring of constituents in gas phase. Opticalfeedback cavityenhanced absorption spectroscopy with. New form of cavity enhanced absorption spectroscopy. In this paper, a compact novel qcl module integrated with a complete laser current and temperature control system for different spectroscopy techniques is presented. Detection limits of similar to 4 ppbv for hono and similar to 14 ppbv for no2 are reported for. Sub100 fs pulses with a repetition rate of 90 mhz are generated by a homebuilt ytterbium fiber laser. Incoherent broadband cavityenhanced absorption spectroscopy ibbceas was used in an openpath configuration in outdoor measurements no 3 and aerosol extinction were measured under polluted conditions in the north china plain during the carebeijing campaign.
Pdf cavity enhanced absorption and cavity enhanced magnetic. Since transmission and losses are minimized by design, we deduce absorption a from energy conservation as follows. Cavity enhanced absorption spectroscopy ceas has similarities with the better known cavity ringdown technique crds which measures the signal decay as a laser pulse emerges through one of the mirrors after successive reflections. Cavityenhanced cantilever enhanced photoacoustic spectroscopy teemu tomberg, a tuomas hieta, b markku vainio a,c and lauri halonen a we have improved the sensitivity of a stateoftheart cantilever enhanced photoacoustic trace gas sensor by combining it with an optical power buildup cavity. We demonstrate incoherent broadband cavity enhanced absorption spectroscopy in the midinfrared wavelength range from 3000 to 3450 nm using an allfiber based supercontinuum source.
The first is a broadband resonator cavity, capable of achieving long effective path lengths over the entire visible wavelength range 370 700 nm. Vibrational rotational states form complex and dense energy. Pdf the paper presents opportunities of cavity enhanced absorption. Cavity enhanced absorption spectrum as recorded with 200 mbar molecular oxygen in a 12cmlong cell at room.
Atmospheric field measurements using cavity enhanced. Some of the most sensitive absorption measurements to date are based on schemes that use a resonant cavity to dramatically increase the path length of a light beam interacting with an absorbing analyte, such as a trace gas. The laser linewidth reduction and frequency locking by selective optical feedback from the resonant cavity field turns out to be particularly advantageous in this spectral range. Cavityenhanced spectroscopy and sensing springerlink. Cavityenhanced absorption spectroscopy and photoacoustic. A new highly sensitive method for incoherent broadband cavityenhanced absorption.
Featre cavityenhanced laser absorption spectrometry for. Thus, a new lightemitting diode ledbased ibbceas was developed herein to measure hcho in. Walsh, dongfeng zhao,a and harold linnartz sackler laboratory for astrophysics, leiden observatory, university of leiden, po box 95, nl 2300 ra. Cavity enhanced ultrafast transient absorption spectroscopy melanie a. After coupling a pulse into the resonator or after switching a cw laser off, the light remains in the cavity for some time, but slowly loses in intensity due to the. We introduce cavity enhanced ultrafast transient absorption spectroscopy, which employs frequency combs and highfinesse optical cavities. For both compounds the absorption is measured between 360 and 380 nm with a compact cavityenhanced spectrometer employing a high power lightemitting diode. Plyler prize for molecular spectroscopy, the bourke lectureship of the royal society of chemistry, and a humboldt senior.
Abstract in recent years, cavity enhanced spectroscopic techniques, such as cavity ringdown spectroscopy crds, cavity enhanced absorption spectroscopy ceas, and broadband cavity enhanced absorption spectroscopy bbceas, have been widely employed as ultrasensitive methods for the measurement of weak absorptions and in the realtime detection of trace species. Onresonant absorption of 89 3% is obtained during cavity length scan fig. The laser light enters this optical cavity when the laser frequency and the frequency of one of the cavity eigenmodes accidentally coincide. Cavityenhanced absorption spectroscopy of molecular oxygen. Laser absorption spectrometry las has many industrial applications. A new cavity based absorption instrument for detection of water isotopologues in the upper. Opticalfeedback cavityenhanced absorption spectroscopy. No 3 was observed at partspertrillion mixing ratios even in the presence of strong aerosol extinction and high humidity. This approach enables absorption spectra to be obtained through the integration of. New developments of broadband cavity enhanced spectroscopic. Sensitive detection of ambient formaldehyde by incoherent. Cavityenhanced absorption for trace gas detection with frontier. Offaxis integrated cavity output spectroscopy, a variant of cavity enhanced las, can be even more effective.
Cavityenhanced detection of molecular absorption under the scheme of wavelength modulation spectroscopy article pdf available in japanese journal of. We report on the performance of a simple cavity enhanced absorption spectroscopy ceas sensor using a continuous wave externalcavity qcl at 7. Absorption spectra of atoms and molecules contain not only structural information but also knowledge about dynamics. New, alternative measurement methods based on cavity enhanced spectroscopy. Cavity enhanced optical frequency comb spectroscopy. Cavity enhanced absorption spectroscopy in the mid.
A new and sensitive setup to swiftly test proposed carriers of the di. Cavity enhanced laser absorption spectrometry for industrial applications by manish gupta, ph. The combination of interband cascade lasers icl with cavity enhanced absorption spectroscopy ceas offers new perspectives in trace analysis and isotope ratio measurements. An optical cavity consists of highly reflective mirrors, which reflect light repeatedly.
Sensitive trace gas detection with cavity enhanced. Sensitive trace gas detection with cavity enhanced absorption spectroscopy using a continuous wave externalcavity quantum cascade laser j. Timeresolved broadband cavityenhanced absorption spectroscopy. Pdf cavityenhanced detection of molecular absorption under. Integrated cavity output spectroscopy icos and cavity enhanced absorption spectroscopy ceas. Precise cavity enhanced absorption spectroscopy a cygan, p wcis lo, s w ojtewicz, p mas lowski, j domys lawska, r s trawinski, r ciury lo, d lisak institute of physics, faculty of physics, astronomy, and informatics, nicolaus copernicus university, grudziadzka 5, 87100 torun, poland email. A new application of incoherent broadband cavity enhanced absorption. Feno provide a new method to monitor the inflammatory status in respiratory.
In this introductory chapter we will begin with an historical outline of the development of cavity enhanced absorption methods, with just enough attention to the applications that either motivated them or became conceivable after their development. Cavity ringdown spectroscopy crds can be implemented with pulsed lasers or with continuous wave cw lasers, where it is sometimes referred to as cavity leakout spectroscopy. Cavity enhanced plasma selfabsorption spectroscopy cepsas is introduced as a sensitive spectroscopic tool. In contrast, the open path configuration has been successfully combined with incoherent broadband cavity enhanced absorption spectroscopy ibbceas across numerous atmospheric simulation chambers in studies of trace gases and aerosols.
One technique, which for this purpose uses a stable optical resonator, is known as cavity enhanced absorption spectroscopy ceas. Recently, two new techniques were introduced for sensitive and selective trace gas detection. They are based on precise measurements of shape of cavity modes broadened and shifted in the vicinity of the absorber placed inside the high nesse cavity. The laser light enters this optical cavity when the laser frequency and the frequency of one of the cavity eigenmodes. By measuring the increase in the rate of decay caused by an.
Cavityenhanced ultrafast transient absorption spectroscopy. However, hcho detection via traditional incoherent broadband cavity enhanced absorption spectroscopy ibbceas is limited by short optical path lengths and weak light intensity. We present a new technique using a frequency comb laser and optical cavities for performing ultrafast transient absorption spectroscopy with improved sensitivity. A new diagnostic tool for light emitting matter anton j. Resonantly enhancing the probe pulses, we demonstrate a sensitivity of. Offaxis icos prevents optical interference within the.
Validation of in situ measurements of atmospheric nitrous. Incoherent broadband cavityenhanced absorption spectroscopy of. Resonant cavityenhanced absorption for optical refrigeration. Combining broadband optical cavity spectroscopy with an open path configuration allows insitu. At present there are many reasons for seeking new methods and technologies that aim to develop new and more. Cavity enhanced absorption and cavity enhanced magnetic. It makes use of efficient multipassing along the same optical path in a highq optical cavity. The proposed technique rests on three main components. Pcfbased cavity enhanced spectroscopic sensors for. The radiation from a scanning narrow band cw laser is. Cavityenhanced laser absorption spectrometry for industrial applications by manish gupta, ph.
Precise cavity enhanced absorption spectroscopy iopscience. Icls cover a midinfrared spectral window 34 m, in between those covered by gainassb diode lasers and quantum cascade lasers qcl, where strong molecular transitions can be found. Incoherent broadband cavity enhanced absorption spectroscopy ibbceas is a useful technique for measuring trace gaseous species in the atmosphere. Atmospheric field measurements using cavity enhanced spectroscopy. Cavity enhanced absorption spectroscopic techniques, based on an arti.
Chapter 8 cavityenhanced direct frequency comb spectroscopy. Offaxis integrated cavity output spectroscopy, a variant of cavityenhanced las, can be even more effective. To achieve their full potential, such experiments must actively lock the probe laser frequency to the cavity and match the source spectral shape and spatial profile. Recently, ibbceas was used to measure concentrations of nitrous acid hono in the troposphere to resolve controversies related to its formation and loss. Recently, ibbceas was used to measure concentrations of nitrous acid hono in the troposphere to resolve controversies related to. Review of scientific instruments 84, 026108 20 note. Cavity enhanced detection of molecular absorption under the scheme of wavelength modulation spectroscopy article pdf available in japanese journal of applied physics 419. Optical cavities are mostly used in such spectroscopic techniques as cavityenhanced absorption spectroscopy ceas and cavity ringdown spectroscopy crds, 20 where the interest is not as much in the optical power as it is in the interaction path length. Allison stony brook university, stony brook, ny 117943400 we present a new technique using a frequency comb laser and optical cavities for performing ultrafast transient absorption spectroscopy with improved sensitivity. Incoherent broadband cavityenhanced absorption spectroscopy ibbceas is a useful technique for measuring trace gaseous species in the atmosphere. Cavity enhanced absorption spectroscopy with broadband. The cavity enhanced absorption spectroscopy technique is a modification of cavity ring down spectroscopy technique where the offaxis adjustment of the resonator is used.
Cavity enhanced spectroscopy technique narrowband broadband pulsed light cavity ringdown spectroscopy crds broadband cavity ringdown spectroscopy bbcrds continuous light integrated cavity output spectroscopy icos broadband cavity enhanced absorption spectroscopy bbceas all of these techniques are described by the same basic equation. Cavityenhanced ultrafast transient absorption spectroscopy melanie a. Cavityenhanced detection of molecular absorption under the scheme of wavelength modulation spectroscopy article pdf available in japanese journal of applied physics 419. Optical resonators optical cavities that are suitable for the ceas are characterized by a high quality factor qfactor 10 4 ensuring several tens of backandforth reflections of light during its decay and. Kirchner, and jun ye jila, national institute of standards and technology and university of colorado, boulder, co 803090440, usa department of physics, university of colorado, boulder, co 803090390, usa. We achieve a quantumnoiselimited absorption sensitivity of 1.
Pdf cavityenhanced detection of molecular absorption. Opticalfeedback cavityenhanced absorption spectroscopy is demonstrated in the midir by using a quantum cascade laser emitting at 4. The technique is realized using incoherent sources of radiation e. Introduction optical spectroscopy has long been the backbone of many applications in physics, chemistry, biology, and environmental sciences. Multicomponent gas detection is performed, and the concentrations of acetylene and methane are retrieved with subppm accuracy. In cavity ringdown spectroscopy, an absorption spectrum is produced. New form of cavity enhanced absorption spectroscopy core. Application of cavity enhanced absorption spectroscopy to the. A new variation of the cavity ringdown spectroscopy technique was developed independently in 1998 in two different groups by okeefe et al.
The cavity enhanced absorption spectroscopy technique is a modification of cavity. Broadband cavityenhanced absorption spectroscopy in the. This item appears in the following collections academic publications 176652 academic output radboud university. As opposed to crd spectroscopy, and similar to cavity enhanced absorption spectroscopy employing high resolution tunable lasers,25. Optical cavities are mostly used in such spectroscopic techniques as cavity enhanced absorption spectroscopy ceas and cavity ringdown spectroscopy crds, 20 where the interest is not as much in the optical power as it is in the interaction path length. Cavity enhanced absorption cea spectroscopy is a fairly new continuous wave cw sensitive absorption technique. Formaldehyde hcho is the most abundant atmospheric carbonyl compound and plays an important role in the troposphere. Examples of recent breakthroughs include the use of frequency combs nobel prize 2005 for cavity enhanced sensing and spectroscopy, the use of novel cavity materials and geometries, the development of optical heterodyne detection techniques combined to active frequencylocking schemes. Application of cavity enhanced absorption spectroscopy to. Ropcke leibniz institute for plasma science and technology inp greifswald, felixhausdorffstr. Bbceas is a new cavitybased absorption technique that uses broadband sources rather than lasers. The article concentrates on liquidphase applications, an interesting new area since most cavitybased absorption studies have.
84 771 841 371 357 29 366 998 1508 328 1481 99 1139 1425 806 693 1161 1219 1011 1104 306 1206 1012 1522 1642 305 971 181 170 1572 309 1168 935 1057 170 1408 677 1458 264 1034 647