Department of Chemistry, Physical & Theoretical Chemistry Laboratory, University of Oxford, Oxford, OX1 3QZ, United Kingdom.
Published: April 2014
AI Article Synopsis
Article Abstract
Broadband cavity-enhanced absorption spectroscopy (BBCEAS) is shown to be a sensitive method for the detection of magnetic field effects (MFEs) in two flavin-based chemical reactions which are simple models for cryptochrome magnetoreceptors. The advantages of optical cavity-based detection and (pseudo-white-light) supercontinuum radiation have been combined to provide full spectral coverage across the whole of the visible spectrum (425 < λ < 700 nm). This region covers the absorbance spectra of flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) as well as their photogenerated radicals. To illustrate the power of this technique, BBCEAS has been used to record the spectral dependence of MFEs for photoinduced radical pairs formed in the intermolecular reaction of FMN with lysozyme and the intramolecular photochemistry of FAD. These reactions have been chosen for their photochemical similarities to cryptochrome proteins which have been proposed as key to the magnetic compass sense of many animals including birds. In experiments performed using low protein concentrations (10 μM) and 1 mm optical path-lengths, absorbance changes as small as 1 × 10(-7) (representing <0.1% MFEs) have been detected with good signal-to-noise offering the prospect of sensitive MFE detection in cryptochrome.
Nitrous acid (HONO) is crucial in atmospheric chemistry as it is a major precursor for hydroxyl radicals (OH), the dominant atmospheric oxidant. Hydroxyl radicals are essential in the formation of secondary air pollutants like ozone and particulate matter. This study presents a newly developed Incoherent Broadband Cavity Enhanced Absorption Spectroscopy (IBBCEAS) system for precise and rapid measurements of HONO and nitrogen dioxide (NO) emissions.
State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012, P. R. China.
Sulfur dioxide (SO) and nitrogen dioxide (NO) are chemical indicators of crop straw combustion as well as significant atmospheric pollutants. It is challenging to promptly detect natural "wildfires" during agricultural production, which often lead to uncontrollable and substantial economic losses. Moreover, both "wildfires" and artificial "straw burning" practices pose severe threats to the ecological environment and human health.
This study investigates the integration of Broadband Cavity Enhanced Absorption Spectroscopy (BBCEAS) with High-Performance Liquid Chromatography (HPLC) to detect synthetic antioxidants; BHA, BHT, and TBHQ in the deep-UV region below 300 nm. The research addresses the need for more sensitive and cost-effective detection methods in HPLC systems, particularly for low analyte concentrations, by exploring BBCEAS as a superior alternative to conventional detectors that often fall short in sensitivity. The sensitivity of the HPLC-BBCEAS system is assessed by calculating the minimum detectable change in the absorption coefficient (αmin) and comparing with those obtained using conventional HPLC and single-wavelength HPLC-CRDS methods.
We report on multi-resonance chirped distributed Bragg reflector (DBR) microcavities. These systems are employed to investigate the light-mater interaction with both intra- and inter-layer excitons of transition metal dichalcogenide (TMDC) bilayer heterostructures. The chirped DBRs consisting of SiO and SiN layers of gradually varying thickness exhibit a broad stopband with a width exceeding 600 nm.
An extremely conspicuous passive power noise stabilization is the first, to the best of our knowledge, discovered in a cavity-enhanced second-harmonic generation (SHG) process. Differing from the SHG as a buffer reservoir, the stronger strength of the nonlinear interaction pushes the power noise suppression level to a higher value and exhibits a broadband noise reduction performance due to the mechanism of dynamic pump suppression in the SHG process. The noise is suppressed to near shot noise limit (SNL) among the kHz to MHz frequency range, accompanied by a maximum noise reduction of 35 dB.
