The Fourier transform and diode laser spectrum of the n 2 band of diazomethane

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Interstellar Molecules: Their Laboratory and Interstellar Habitat /

This book deals with the astrophysics and spectroscopy of the interstellar molecules. In the introduction, overview and history of interstellar observations are described in order to help understanding how the modern astrophysics and molecular spectroscopy have been developed interactively. The recent progress in the study of this field, after the 4th Cologne-Bonn-Zermatt symposium 2003 is briefly summarized. Furthermore, the basic knowledge of molecular spectroscopy, which is essential to correctly comprehend the astrophysical observations, is presented in a compact form

Molecular shell formation by supernova remnants in the Galactic center: what we learn from the case of W44

Recent high resolution CO images of the Galactic center (GC) molecular clouds reveal many arc and/or shell structures. A considerable fraction of them may most probably be formed by an interaction between supernova remnants (SNRs) and molecular clouds. Studies of such cases in less confused areas are needed to clarify this picture. Our study of the SNR W44 supports this SNR-induced shell formation scenario in the GC. By using the Tokyo-NRO 60-cm survey telescope, the 45-m telescope at Nobeyama,and the 15-m JCMT on Mauna Kea, we established that W44 is the first unambiguous example of interaction between a SNR and giant molecular clouds. Our millimeter and submillimeter observations revealed that the SNR changed the surface of the giant molecular clouds into filaments of shocked molecular gas. They run perpendicular to the direction of the SNR expansion. Sequential interactions between SNRs and the molecular cloud which are expected in the GC may further form these molecular filaments into networks, which are observed as shell/arc structures often made of high density molecular gas

Submillimeter-Wave Absorption Spectroscopy of the Ar-CO Complex: Detection of the van der Waals Bending Vibration

Van der Waals bending rovibrational transitions of the Ar-CO complex were observed between 308 and 383 GHz using submillimeter-wave absorption spectroscopy in a pulsed supersonic jet. The submillimeter radiation was generated by a phase-stabilized backward wave oscillator source. Fourteen transitions of the P and R branch of the bending vibration were measured with an accuracy of about 100 kHz. The frequencies were fitted using effective molecular parameters including the band origin and the rotational constants for the ground state and for the excited bending vibrational state. © 1997 Academic Press.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Phase locked backward wave oscillator pulsed beam spectrometer in the submillimeter wave range

We have developed a new submillimeter wave pulsed molecular beam spectrometer with phase stabilized backward wave oscillators (BWOs). In the frequency ranges of 260-380 and 440-630 GHz, the BWOs output power varies between 3 and 60 mW. Part of the radiation was coupled to a novel designed harmonic mixer for submillimeter wavelength operation, which consists of an advanced whiskerless Schottky diode driven by a harmonic of the reference synthesizer and the BWO radiation. The resulting intermediate frequency of 350 MHz passed a low noise high electron mobility transistor amplifier, feeding the phase lock loop (PLL) circuit. The loop parameters of the PLL have been carefully adjusted for low phase noise. The half power bandwidth of the BWO radiation at 330 GHz was determined to be as small as 80 MHz, impressively demonstrating the low phase noise operation of a phase locked BWO. A double modulation technique was employed by combining an 80 Hz pulsed jet modulation and a 10-20 kHz source modulation of the BWO and reaching a minimum detectable fractional absorption of 2 × 10-7. For the first time, a number of pure rotational (Ka=3←2, Ka=4←3) and rovibrational transitions in the van der Waals bending and stretching bands of the Ar-CO complex were recorded. © 1998 American Institute of Physics.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Planar diode multiplier chains for THz spectroscopy

High-resolution laboratory spectroscopy is utilized as a diagnostic tool to determine noise and harmonic content of balanced [9]-[11] and unbalanced [12]-[14] multiplier designs. Balanced multiplier designs suppress unintended harmonics more than -20dB. Much smaller values were measured on unbalanced multipliers