97 research outputs found
Broadly, independent-tunable, dual-wavelength mid-infrared ultrafast optical parametric oscillator
We demonstrate a two-crystal mid-infrared dual-wavelength optical parametric
oscillator, synchronously pumped by a high power femtosecond Yb:fiber laser.
The singly-resonant ring cavity, containing two periodically poled lithium
niobate crystals, is capable of generating two synchronized idler wavelengths,
independently tunable over 30 THz in the 2.9 - 4.2 {\mu}m wavelength region,
due to the cascaded quadratic nonlinear effect. The independent tunability of
the two idlers makes the optical parametric oscillator a promising source for
ultrafast pulse generation towards the THz wavelength region, based on
different frequency generation. In addition, the observed frequency doubled
idler within the crystal indicates the possibility to realize a broadband
optical self-phase locking between pump, signal, idler and higher order
generated parametric lights
ONLINE GAS MONITORING USING A MID-INFRARED OPO BASED DUAL COMB SPECTROMETER
A dual-frequency comb-based spectrometer for the mid-infrared (3-5 micrometer) wavelength region will open many opportunities for spectroscopic applications. Non-linear conversion provides a wide spectral coverage in the mid-infrared using Optical Parametric Oscillators, keeping the optical properties of the well-established near infrared frequency combs with good frequency accuracy, high spectral resolution at seconds time scale. A number of challenges remain when OPOs are used for optical conversion, because the OPO cavity generate frequency and intensity fluctuation in the combs. Here, we present how these variations are measured and used, in real-time, to correct the recorded broadband spectrum. By monitoring the frequency and amplitude variations of a single absorption line in a reference gas cell, each individual spectrum is normalized in amplitude and corrected by an offset-frequency. As such, real-time averaging is achieved over minutes with minor losses in spectral resolution or degradation, leading to an improvement in spectral resolution. A high-to-noise ratio of about 2400 is achieved with such spectral resolution, demonstrating the efficiency of the proposed method
Time-resolved mid-infrared dual-comb spectroscopy
Dual-comb spectroscopy can provide broad spectral bandwidth and high spectral
resolution in a short acquisition time, enabling time-resolved measurements.
Specifically, spectroscopy in the mid-infrared wavelength range is of
particular interest, since most of the molecules have their strongest
rotational-vibrational transitions in this "fingerprint" region. Here we report
time-resolved mid-infrared dual-comb spectroscopy for the first time, covering
~300 nm bandwidth around 3.3 {\mu}m with 6 GHz spectral resolution and 20
{\mu}s temporal resolution. As a demonstration, we study a CH4/He gas mixture
in an electric discharge, while the discharge is modulated between dark and
glow regimes. We simultaneously monitor the production of C2H6 and the
vibrational excitation of CH4 molecules, observing the dynamics of both
processes. This approach to broadband, high-resolution, and time-resolved
mid-infrared spectroscopy provides a new tool for monitoring the kinetics of
fast chemical reactions, with potential applications in various fields such as
physical chemistry and plasma/combustion analysis.Comment: 21 page, 6 figure
Reactive oxygen production induced by near-infrared radiation in three strains of the Chl d-containing cyanobacterium Acaryochloris marina
Cyanobacteria in the genus Acaryochloris have largely exchanged Chl a with Chl d, enabling them to harvest near-infrared radiation (NIR) for oxygenic photosynthesis, a biochemical pathway prone to generate reactive oxygen species (ROS). In this study, ROS production under different light conditions was quantified in three Acaryochloris strains (MBIC11017, HICR111A and the novel strain CRS) using a real-time ethylene detector in conjunction with addition of 2-keto-4-thiomethylbutyric acid, a substrate that is converted to ethylene when reacting with certain types of ROS. In all strains, NIR was found to generate less ROS than visible light (VIS). More ROS was generated if strains MBIC11017 and HICR111A were adapted to NIR and then exposed to VIS, while strain CRS demonstrated the opposite behavior. To our knowledge, this is the first study of ROS generation associated with NIR-driven oxygenic photosynthesis and it suggests that Acaryochloris can avoid a considerable amount of light-induced stress by using NIR instead of VIS for its photosynthesis, adding further evolutionary arguments to their widespread appearance
Use of a Laser-Driven Photoacoustic Detection System for Measurement of Ethylene Production in Cymbidium
ABA Suppresses Botrytis cinerea Elicited NO Production in Tomato to Influence H2O2 Generation and Increase Host Susceptibility
Contains fulltext :
158667.pdf (publisher's version ) (Open Access)12 p
Inhibition by Ethylene of Auxin-Promotion of Flower Bud Formation in Tobacco Explants Is Absent in Plants Transformed by Agrobacterium rhizogenes
Reactive oxygen production induced by near-infrared radiation in three strains of the Chl <em>d</em><i>-</i>containing cyanobacterium <i>Acaryochloris marina</i>
Cyanobacteria in the genus Acaryochloris have largely exchanged Chl a with Chl d, enabling them to harvest near-infrared-radiation (NIR) for oxygenic photosynthesis, a biochemical pathway prone to generate reactive oxygen species (ROS). In this study, ROS production under different light conditions was quantified in three Acaryochloris strains (MBIC11017, HICR111A and the novel strain CRS) using a real-time ethylene detector in conjunction with addition of 2-keto-4-thiomethylbutyric acid, a substrate that is converted to ethylene when reacting with certain types of ROS. In all strains, NIR was found to generate less ROS than visible light (VIS). More ROS was generated if strains MBIC11017 and HICR111A were adapted to NIR and then exposed to VIS, while strain CRS demonstrated the opposite behavior. This is the very first study of ROS generation and suggests that Acaryochloris can avoid a considerable amount of light-induced stress by using NIR instead of VIS for its photosynthesis, adding further evolutionary arguments to their widespread appearance
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