High-sensitivity absorption spectroscopy of lithium niobate crystals in the near and mid infrared regime

Lithium niobate (LiNbO3) possesses several useful electrical and optical properties, making it a suitable material for a wide range of applications like electro-optic modulators and nonlinear-optical devices. The latter are operated in the transparency window of LiNbO3 between 450 and 4000 nm wavelength. The availability of high-power pump lasers has made nonlinear frequency conversion processes more and more effective. With increasing pump powers, however, even weak absorption due to residual impurities or crystal imperfections may lead to thermal or mechanical malfunction of the devices. Proper characterization of the materials is of scientific interest and practical relevance

Rapid regulation of the methylerythritol 4-phosphate pathway during isoprene synthesis

More volatile organic carbon is lost from plants as isoprene than any other molecule. This flux of carbon to the atmosphere affects atmospheric chemistry and can serve as a substrate for ozone production in polluted air. Isoprene synthesis may help lea

INFRARED SPECTRUM OF THE STRONGLY CORIOLIS COUPLED ν2\nu_{2} AND ν4\nu_{4} VIBRATIONAL STATES OF CH3+{CH_{3}}^{+}

1. D.J. DeFrees and A.D. McLean, J. Chem. Phys. 82, 333 (1985) 2. P. Botschwina, in Ion and Cluster Ion Spectroscopy and Structure, edited by J.P. Maier (Elvier, Amsterdam, 1989) 3. W.P. Kraemer and V. Spirko, J. Molec. Spec. 149, 235 (1991) 4. P.B. Davies and D.M. Smith, J. Chem. Phys. 100, 6166 (1994)Author Institution: The University of Chicago, Chicago, IL 60637-1403.; Technischen Universität Berlin, Berlin 10623 Germany.The $\nu_{2}$ and $\nu_{4}$ bending vibrations of the methyl cation ${CH_{3}}^{+}$ are strongly coupled by Coriolis interaction because of the near degeneracy of the two vibrational modes. Ab initio theoretical $studies^{1,2,3}$ have predicted them to be within $1-20 cm^{-1}$. This is somewhat similar to the case of SiH3+ reported by Davies and $Smith^{4}$. The patchy coverage of the diode lasers and the strong Coriolis coupling make the analysis difficult. From $1503-1297 cm^{-1}, 95$ lines have been observed in a liquid cooled $He/H_{2}/CH_{4}$ plasma discharge using 5 diode lasers and velocity modulation. Six ${^{r}}Q(J, K = 0)$ transitions in the $\nu_{4}$ band were readily assigned since the $\nu_{4}$ levels involved in these transitions are free of the strong Coriolis interaction because of the absence of odd J, K = 0 levels in the $\nu_{2}$ vibrational state due to the Pauli exclusion principle. PP(J = K) transitions in the $\nu_{4}$ band are also free of the interaction and can be analyzed by using only diagonal matrix elements. A complete analysis of the bands is in progress and will be reported at the meeting. la. Feodor Lynen Fellow (Alexander von Humbolt Foundation)

Photoacoustic detection of weak absorption in lithium niobate

This paper presents a different approach: pulsed-laser photoacoustic (PA) spectroscopy with piezoelectric (PZT) sensors is used to determine the absorption through the amount of the energy deposited in the sample. This results in a simple experimental setup. Here, a frequency doubled Nd:YAG laser (λ = 532 nm) was used. The setup allows the variation of pulse energy (10 μJ to 100 mJ), pulse duration (5 to 20 ns) and beam diameter (0.1 mm to 4 mm) for a systematic investigation of the PA signal generated in the LiNbO3 crystals

Cellulysin from the plant parasitic fungus Trichoderma viride elicits volatile biosynthesis in higher plants via the octadecanoid signalling cascade

Cellulysin, a crude cellulase from the plant parasitic fungus Trichoderma viride, induces the biosynthesis of volatiles in higher plants (Nicotiana plumbaginifolia, Phaseolus lunatus, and Zea mays) when applied to cut petioles by the transpiration stre

On-line monitoring of biogenic isoprene emissions using photoacoustic spectroscopy

Isoprene (C5H8) is one of the most important biogenic volatile organic compounds (VOCs) in the atmosphere. To calculate the impact of isoprene on atmospheric processes models have been developed that describe the isoprene release from plants. Measureme