Cavity-enhanced absorption

Cavity-enhanced absorption techniques are also applied in flames in the near infrared [22-25]. The multiple absorption paths provided with these techniques are the reason for their superb sensitivity in the ppb range. Absolute concentrations can be obtained, provided the absorption coefficient for the respective transition is known. CRDS can be used in conjunction with other laser-based combustion diagnostics for... 

Peeters, R., Berden, G., and Meijer, G., Near-infrared cavity enhanced absorption spectroscopy of hot water and OH in an oven and in flames, Appl. Phys. B, 73,65,2001. 

Seletskiy, D.V., Hasselbeck, M.P., Sheik-Bahae, M., 2010a. Resonant cavity-enhanced absorption for optical refrigeration. Appl. Phys. Lett. 96(18), 181106-181103. 

McGarvey T., Conjusteau A., and Mabuchi H., Finesse and sensitivity gain in cavity-enhanced absorption spectroscopy of biomolecules in solution. Opt Express, 14,10441-10451 (2006). 

Muiier C, Machtie P and Heim C A 1994 Enhanced absorption within a cavity. A study of thin dye iayers with the surface forces apparatus J. Rhys. Chem. 98 11 119-25... 

Methods of Cavity-Enhanced Laser Absorption Spectroscopy Using Microresonator Whispering-Gallery Modes... 

Farca, G. Shopova, S. I. Rosenberger, A. T., Cavity enhanced laser absorption spectroscopy using microresonator whispering gallery modes, Opt. Express 2007, 15, 17443 17448... 

Freely suspended liquid droplets are characterized by their shape determined by surface tension leading to ideally spherical shape and smooth surface at the subnanometer scale. These properties suggest liquid droplets as optical resonators with extremely high quality factors, limited by material absorption. Liquid microdroplets have found a wide range of applications for cavity-enhanced spectroscopy and in analytical chemistry, where small volumes and a container-free environment is required for example for protein crystallization investigations. This chapter reviews the basic physics and technical implementations of light-matter interactions in liquid-droplet optical cavities. 

Poly(alkyl-cyanoacrylate) Nanoparticles The applications of poly(alkyl-cyanoacrylate) nanoparticles have been reviewed elsewhere and therefore only representative examples are described [102], Because of their adhesive properties, nanoparticles have the potential to prophylactically treat candidiasis of the oral cavity [121], Not surprisingly, poly(alkyl-cyanoacrylate) nanoparticles have been used to deliver drugs to tumors [122], Enhanced absorption and prolonged hypoglycemic effect were observed when insulin was delivered in poly(alkyl-cyanoacrylate) nanoparticles [121], Nuclear accumulation of antisense oligonucleotides into vascular smooth muscle cells was increased when delivered using poly(alkyl-cyanoacrylate) nanoparticles [123]. Dextran-coated poly(alkyl-... 

An extremely sensitive technique able to detect the nature of radical pairs in a photochemical reaction is called chemically induced dynamic nuclear polarization (CIDNP), which depends on the observation of an enhanced absorption in a nuclear magnetic resonance (NMR) spectrum of the sample, irradiated in situ, in the cavity of a NMR spectrometer. The background to and interpretation of CIDNP are discussed by Gilbert and Baggott (28). 

The photoreduction of furil in 2-propanol as solvent and proton donor within the cavity of an ESR spectrophotometer allows the existence of a radical to be demonstrated.25 This radical is formally identical with the chemically generated radical in Scheme 60 (Part I). With the stronger acid, phenol in place of the alcohol three radicals appear compound 9 is one.25 With pentachlorophenol the product is found to be spin polarized CIDNP spectra show that initially emissive protons relax to enhanced absorption and vice versa.26... 

Instead of absorption, weak emission lines can also be detected with the intracavity techniques [26]. If this light is injected into specific modes of the multimode laser, the intensity of these modes will increase for observation times t mode-coupling with other modes. Cavity-enhanced spectroscopy in optical fibres have been reported in [32, 33]. 

New absorption methods, like intracavity spectroscopy, cavity-ring-down and cavity-enhanced spectroscopy, have demonstrated very high sensitivities in laboratory measurements with DLs. An ultrasensitive technique that combines external cavity enhancement and FM spectroscopy has been developed recently. This method, which has been called NICE-OHMS. or noise-immune cavity-enhanced optical heterodyne molecular spectroscopy, is based on frequency modulation of the laser at the cavity free-spectral-range frequency or its multiple. The MDA of 5x 10 1 X 10 cm ) in the detection of narrow... 

Hu J., Carlie N., Petit L., Agarwal A., Richardson K., and Kimerling L. C., Cavity-enhanced IR absorption in planar chalcogenide glass microdisk resonators Experiment and analysis, RID B-9534-2008, RID A-6012-2011,/. Lightwave TechnoL, 27, 5240-5245 (2009). 

Nitkowski A., Chen L., and Lipson M., Cavity-enhanced on-chip absorption spectroscopy using microring resonators. Opt Express, 16, 11930-11936(2008). 

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