69 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
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
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
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
Roadmap on ultrafast optics
Contains fulltext :
166150.pdf (publisher's version ) (Closed access
Laser photoacoustic detection allows in planta detection of nitric oxide in tobacco following challenge with avirulent and virulent Pseudomonas syringae pathovars.
We demonstrate the use of laser photoacoustic detection (LPAD) as a highly sensitive method to detect in planta nitric oxide ( . NO) production from tobacco (Nicotiana tabacum . NO 1 O 3 / NO 2 1 O 2 ). The utility of the LPAD method was shown by examination of a nonhost hypersensitive response and a disease induced by Pseudomonas syringae (P. s.) pv phaseolicola and P. s. pv tabaci in tobacco. . NO was detected within 40 min of challenge with P. s. pv phaseolicola, some 5 h before the initiation of visible tissue collapse. The wildfire tobacco pathogen P. s. pv tabaci initiated . NO generation at 2 h postinfection. The use of . NO donors, the scavenger CPTIO ([4-carboxyphenyl]-4,5-dihydro-4,4,5,5-tetramethyl-3-oxide), and the mammalian nitric oxide synthase inhibitor L-NMMA (N G -monomethyl-L-arginine) indicated that . NO influenced the kinetics of cell death and resistance to both avirulent and virulent bacteria in tobacco. These observations suggest that
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