Measurement of integrated absorption cross-section, oscillator strength and number density of caffeine in coffee beans by integrated absorption coefficient technique

(1) Background: Optical absorption cross-section—the absolute absorption intensity specific to each molecule—of nucleic acid bases enables us to estimate the reaction yields of DNA lesions induced by the exposure to not only photons but also ionizing radiations. However, it was unknown in the energy region exceeding ~10 eV (wavelength < ~120 nm). (2) Methods: Thin films of DNA bases—thymine and guanine—were prepared using a vacuum sublimation technique. Absorption spectra of these films were measured in the energy region from 3.1 to 250 eV (5–400 nm) at the synchrotron radiation facility UVSOR. (3) Results: The absorption spectra of both bases exhibited prominent absorption peaks around 20 eV and smaller peaks in the energy region below 10 eV. The determined optical oscillator strength distribution was verified to be reasonable based on the Thomas–Reiche–Kuhn oscillator strength sum rule. (4) Conclusion: Most of the oscillator strength distribution was positioned in the measured energy region, and therefore the absorption spectra significantly contributed to the quantitative study for the photo and radiation-chemical reactions of DNA.

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Oscillator strength and absorption cross-section of core-shell cubic quantum dot for intraband transition

2015 International Conference on Microwave and Photonics (ICMAP) ◽

10.1109/icmap.2015.7408720 ◽

2015 ◽

Author(s):

Arpan Deyasi ◽

N. R. Das

Keyword(s):

Quantum Dot ◽

Oscillator Strength ◽

Cross Section ◽

Absorption Cross Section ◽

Core Shell ◽

Absorption Cross ◽

Intraband Transition

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Determination of black carbon mass concentration from aerosol light absorption using variable mass absorption cross-section

10.5194/amt-2020-337 ◽

2020 ◽

Author(s):

Weilun Zhao ◽

Wangshu Tan ◽

Gang Zhao ◽

Chuanyang Shen ◽

Yingli Yu ◽

...

Keyword(s):

Absorption Coefficient ◽

Black Carbon ◽

Cross Section ◽

Light Absorption ◽

Absorption Cross Section ◽

Traditional Method ◽

Mass Concentration ◽

New Method ◽

Absorption Cross ◽

Light Absorption Coefficient

Abstract. Atmospheric black carbon (BC) is the strongest visible solar radiative absorber in the atmosphere, exerting significant influences on the earth’s radiation budget. The mass absorption cross-section (MAC) is a crucial parameter for converting light absorption coefficient (bab) to mass equivalent BC concentration (mBC). Traditional filter-based instrument, such as AE33, uses a constant MAC of 7.77 m2/g to derive mBC, which may lead to uncertainty in mBC. In this paper, a new method of converting light absorption coefficient to BC mass concentration is proposed by incorporating the variations of MAC attributed to the influences of aerosol coating state. Mie simulation showed that MAC varied dramatically with different core-shell structures. We compared our new method with traditional method during a field measurement at a site of North China Plain. The results showed that the MAC was smaller (larger) than 7.77 m2/g for particle smaller (larger) than 280 nm, resulting in BC mass size distribution derived from new method was higher (lower) than traditional method for particle smaller (larger) than 280 nm. Size-integrated BC mass concentration derived from new method was 16 % higher than traditional method. Sensitivity analysis indicated that the uncertainty in mBC caused by refractive index (RI) was with in 35 % and the imaginary part of RI had dominant influence on the derived mBC. This study emphasizes the necessity to take variations of MAC into account when deriving mBC from bab and can help constrain the uncertainty in mBC measurements.

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Photolysis of frozen iodate salts as a source of active iodine in the polar environment

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-15-27917-2015 ◽

2015 ◽

Vol 15 (19) ◽

pp. 27917-27942 ◽

Cited By ~ 2

Author(s):

O. Gálvez ◽

M. T. Baeza-Romero ◽

M. Sanz ◽

A. Saiz-Lopez

Keyword(s):

Ir Spectroscopy ◽

Absorption Coefficient ◽

Ir Spectra ◽

Cross Section ◽

Absorption Cross Section ◽

Low Temperatures ◽

Ir Absorption ◽

Absorption Cross ◽

Polar Environment ◽

First Time

Abstract. Reactive halogens play a key role in the oxidation capacity of the polar troposphere. However, sources and mechanisms, particularly those involving active iodine, are still poorly understood. In this paper, the photolysis of an atmospherically relevant frozen iodate salt has been experimentally studied using infrared (IR) spectroscopy. The samples were generated at low temperatures in the presence of different amounts of water. The IR spectra have confirmed that under near-UV/Vis radiation iodate is efficiently photolyzed. The integrated IR absorption coefficient of the iodate anion on the band at 750 cm−1 has been measured to be A = 9.5 × 10−17 cm molec−1. Using this value, a lower limit of the integrated absorption cross section of iodate, in an ammonium frozen salt, has been estimated for the first time at wavelengths relevant for tropospheric studies (σ = 1.1 × 10−20 cm2 nm molec−1 from 300 to 900 nm). According to this, we suggest that the photolysis of iodate in frozen salt can potentially provide a pathway for the release of active iodine to the polar atmosphere.

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