Photovoltaic determination of optical‐absorption coefficient in CdTe

1977 ◽  
Vol 48 (2) ◽  
pp. 829-830 ◽  
Author(s):  
Kim Mitchell ◽  
Alan L. Fahrenbruch ◽  
Richard H. Bube
Keyword(s):  
Optical Absorption ◽  
Absorption Coefficient ◽  
Optical Absorption Coefficient

Quantitative photopyroelectric out-of-phase spectroscopy of amorphous silicon thin films deposited on crystalline silicon

1991 ◽  
Vol 69 (3-4) ◽  
pp. 317-323 ◽  
Author(s):  
Constantinos Christofides ◽  
Andreas Mandelis ◽  
Albert Engel ◽  
Michel Bisson ◽  
Gord Harling
Keyword(s):  
Thin Films ◽  
Optical Absorption ◽  
Absorption Coefficient ◽  
Dynamic Range ◽  
Crystalline Silicon ◽  
Optical Absorption Coefficient ◽  
Si Substrates ◽  
Silicon Thin Films ◽  
Background Compensation

A photopyroelectric spectrometer with real-time and(or) self-normalization capability was used for both conventional transmission and thermal-wave spectroscopic measurements of amorphous Si thin films, deposited on crystalline Si substrates. Optical-absorption-coefficient spectra were obtained from these measurements and the superior dynamic range of the out-of-phase (quadrature) photopyroelectric signal was established as the preferred measurement method, owing to its zero-background compensation capability. An extension of a photopyroelectric theoretical model was established and successfully tested in the determination of the optical absorption coefficient and the thermal diffusivity of the sample under investigation. Instrumental sensitivity limits of βt ≈ 5 × 10−3 were demonstrated.

Photoacoustic operation modes for determination of absorption spectra of SiGe mixed crystals

2010 ◽  
Vol 18 (2) ◽  
Author(s):  
M. Maliński ◽  
Ł. Chrobak
Keyword(s):  
Optical Absorption ◽  
Absorption Coefficient ◽  
Absorption Spectra ◽  
Optical Absorption Coefficient ◽  
Optical Absorption Spectra ◽  
Experimental Transmission ◽  
Photoacoustic Spectra ◽  
Advantages And Disadvantages ◽  
Transmission And Absorption

AbstractThis paper presents comparison of two photoacoustic modes of determination of optical absorption spectra of semiconductors illustrated with the results obtained for SiGe crystals. Experimental transmission and absorption photoacoustic spectra of SiGe crystals as well as appropriate models for determination of optical absorption coefficient spectra are given. The idea and experimental set-up of the analyzed methods are presented too. From the fitting procedure of theoretical characteristics to experimental transmission and absorption photoacoustic spectra and after computations of the optical absorption coefficient spectra, three components of the optical absorption coefficient spectra of SiGe crystals were identified, i.e., band to band transitions, Urbach tail and free carriers absorption. Their parameters are given and discussed in the paper. At the end, the advantages and disadvantages of both methods are discussed. To the best of our knowledge, such a comparison of the two PA methods of determination of the optical absorption spectra has not been done before.

scholarly journals Determination of the characteristic inactivation fluence for SARS-CoV-2 under UV-C radiation considering light absorption in culture media

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Juan Carlos Martínez-Antón ◽  
Alejandro Brun ◽  
Daniel Vázquez ◽  
Sandra Moreno ◽  
Antonio A. Fernández-Balbuena ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Optical Absorption ◽  
Absorption Coefficient ◽  
Culture Media ◽  
Optical Absorption Coefficient ◽  
Geometrical Shape ◽  
Experimental Conditions ◽  
Optical Irradiation ◽  
Uv C

AbstractThe optical absorption coefficient of culture media is critical for the survival analysis of pathogens under optical irradiation. The quality of the results obtained from experiments relies on the optical analysis of the spatial distribution of fluence which also depends on the geometry of the sample. In this contribution, we consider both the geometrical shape and the culture medium’s absorption coefficient to evaluate how the spatial distribution of optical radiation affects pathogens/viruses. In this work, we exposed SARS-CoV-2 to UV-C radiation ($$\lambda$$ λ = 254 nm) and we calculated—considering the influence of the optical absorption of the culture medium—a characteristic inactivation fluence of $$F_i$$ F i = 4.7 J/m2, or an equivalent 10% survival (D90 dose) of 10.8 J/m2. Experimentally, we diluted the virus into sessile drops of Dulbecco’s Modified Eagle Medium to evaluate pathogen activity after controlled doses of UV irradiation. To validate the optical absorption mode, we carried out an additional experiment where we varied droplet size. Our model—including optical absorption and geometrical considerations—provides robust results among a variety of experimental situations, and represents our experimental conditions more accurately. These results will help to evaluate the capability of UV disinfecting strategies applied to a variety of everyday situations, including the case of micro-droplets generated by respiratory functions.

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