Pure Rotational Spectrum of HCN in the Terahertz Region: Use of a New Planar Schottky Diode Multiplier

Maiwald, Frank; Lewen, Frank; Ahrens, V.; Beaky, M. M.; Gendriesch, R.; Koroliev, A.N.; Negirev, A. A.; Paveljev, D.G.; Vowinkel, B.; Winnewisser, G.

doi:10.1006/jmsp.2000.8118

Cited by 42 publications

(27 citation statements)

References 12 publications

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“…Hence, several techniques have been employed to cover this large spectral range. In the regime from 64 ± 178 GHz, a commercial spectrometer was used, [34] while radiation in the shorter millimeter-wave regime from 180 ± 208 GHz was generated by employing a commercial 4 mm-wave synthesizer in connection with a planar Schottky Diode Multiplier [35] to make use of the third harmonic of the fundamental. The majority of lines were measured in the frequency region from 480 ± 945 GHz by employing the Cologne Terahertz Spectrometer.…”

Section: Mass-spectrometric Instrumentationmentioning

confidence: 99%

Gas‐Phase Detection of HSOH: Synthesis by Flash Vacuum Pyrolysis of Di‐tert‐butyl Sulfoxide and Rotational‐Torsional Spectrum

Winnewisser

Lewen

Thorwirth

et al. 2003

Chemistry A European J

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Gas-phase oxadisulfane (HSOH), the missing link between the well-known molecules hydrogen peroxide (HOOH) and disulfane (HSSH), was synthesized by flash vacuum pyrolysis of di-tert-butyl sulfoxide. Using mass spectrometry, the pyrolysis conditions have been optimized towards formation of HSOH. Microwave spectroscopic investigation of the pyrolysis products allowed-assisted by high-level quantum-chemical calculations--the first measurement of the rotational-torsional spectrum of HSOH. In total, we have measured approximately 600 lines of the rotational-torsional spectrum in the frequency range from 64 GHz to 1.9 THz and assigned some 470 of these to the rotational-torsional spectrum of HSOH in its ground torsional state. Some 120 out of the 600 lines arise from the isotopomer H(34)SOH. The HSOH molecule displays strong c-type and somewhat weaker b-type transitions, indicating a nonplanar skew chain structure, similar to the analogous molecules HOOH and HSSH. The rotational constants (MHz) of the main isotopomer (A=202 069, B=15 282, C=14 840), determined by applying a least-squares analysis to the presently available data set, are in excellent agreement with those predicted by quantum-chemical calculations (A=202 136, B=15 279, C=14 840). Our theoretical treatment also derived the following barrier heights against internal rotation in HSOH (when in the cis and trans configurations) to be V(cis) approximately equal to 2216 cm(-1) and V(trans) approximately equal to 1579 cm(-1). The internal rotational motion results in detectable torsional splittings that are dependent on the angular momentum quantum numbers J and K(a).

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Section: Mass-spectrometric Instrumentationmentioning

confidence: 99%

Gas‐Phase Detection of HSOH: Synthesis by Flash Vacuum Pyrolysis of Di‐tert‐butyl Sulfoxide and Rotational‐Torsional Spectrum

Winnewisser

Lewen

Thorwirth

et al. 2003

Chemistry A European J

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“…However, the present sources of THz radiation present "hurdles" because of their limited tunable bandwidth and output power, and some require fragile, large, and expensive femtosecond lasers or even particle accelerators (Zhang, 2002). Some of the methods that have been used to generate THz radiation are backward wave oscillators with chains of frequency multipliers (Maiwald et al, 2000), the Smith-Purcell Effect (Mross et al, 2003), quantum cascade lasers (Davies et al, 2002), synchrotron radiation from high-energy accelerators (Carr et al, 2002), bulk electro-optic rectification and ultrafast charge transport in semiconductors (Davies et al, 2002), and photomixing in semiconductors (Verghese et al, 1997). For example, photomixing (optical heterodyning) of two lasers at different wavelengths in low-temperature-grown (LTG) GaAs at the feed point of an antenna can generate an output power of only 1 µW at 1 THz, which falls off by 12 dB per octave or 1/F 4 at higher frequencies (F), so the power is reduced to 100 pW at 10 THz.…”

Section: Introductionmentioning

confidence: 99%

Broadband Terahertz Source Based on Photomixing in Laser-Assisted Field Emission with Clusters of Carbon Nanotubes

Hagmann¹

2010

Carbon Nanotubes

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“…The diode resistance includes the resistances of the semiconductor bulk, contact connections, and diode outputs. At present, the capacitance of a Schottky diode with an active-region area of about a few squared microns amounts to no less than 3 fF [13][14][15], whereas a decrease in the diode series resistance with increasing semiconductor doping is limited by the dope concentration 5 · 10 17 cm −3 [14,15].…”

mentioning

confidence: 99%

“…On the one hand, the limiting frequency is determined by the features of physical processes taking place in the semiconductor structure, in particular by the inertia of electrons during their transit through the active region in the case of Schottky diodes. Thus, the transit time for the best diodes is about 1 ps [15]. On the other hand, the limiting frequency is largely stipulated by the influence of the parasitic capacitance C and series resistance R s of the diode: f o = 1/(2πR s C).…”

mentioning

confidence: 99%

“…The submillimeter-wave synthesizer described for the first time in [9] and operated at frequencies of up to 840 GHz has 6 loops of frequency multiplication. Usually, planar semiconductor Schottky diodes are used as a nonlinear element in harmonic mixers of the terahertz frequency range [10][11][12][13][14][15][16]. However, application of Schottky diodes in the terahertz range requires an increase in the limiting operating frequency f o of the diode (the upper boundary of the diode operating range), which is impeded by a number of existing restrictions.…”

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confidence: 99%

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Development and design of a phase-locked loop in the subterahertz and terahertz ranges for a harmonic of the signal of a centimeter-wave synthesizer

Вакс

Koshurinov

Pavel'ev

et al. 2005

Radiophys Quantum Electron

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We describe a phase-locked loop of a backward-wave oscillator in the range 667-857 GHz for the 34th-45th harmonic of the reference signal of a centimeter-wave synthesizer. Multiplication of the reference-synthesizer frequency in the phase-locked loop is performed by using a subharmonic mixer based on semiconductor superlattices. The mixer, operated at room temperature, has a nonlinear electron conductance.Great interest in the terahertz range, shown by many researchers, is stipulated by new possibilities of studies, primarily in the field of microwave spectroscopy of high and superhigh resolution. Development of new terahertz devices also stimulates radio-astronomical studies to a considerable extent [1,2].At present, studies in the field of microwave and radio spectroscopy are restricted by the limited access to terahertz devices. First of all, this is related to the fact that until recently, effective sources and detectors of terahertz radiation have been absent. The majority of terahertz sources had either low intensity, as thermal sources, or were bulky and not tunable with respect to frequency, as molecular lasers. The only source of wideband coherent radiation, a backward-wave oscillator (BWO), operates at frequencies of up to 1250 GHz. Recently, a spectrometer based on a femtosecond laser [3] and capable of solving various problems such as spectroscopy of biological molecules [4], liquids [5,6], and solids [7,8] has been developed. The spectral resolution of such spectrometers does not exceed 1 GHz, which is insufficient for high-resolution spectroscopy.The necessary condition for achieving high and superhigh resolution in spectroscopy is the presence of a source of radiation with a narrow spectrum and exact setting of the radiation frequency. The spectroscopic requirements to the parameters of the frequency and spectrum of a high-quality radiation source are usually determined by the necessity to resolve the Doppler line broadening (of the order of 10 −6 ) and to measure the frequencies of spectral lines and the shifts of their centers with accuracy up to 10 −8 -10 −10 . Development of terahertz sources with a narrow spectrum and exact setting of the frequency with the subsequent transfer of the radiation frequency to the high-frequency region of the terahertz range by multiplication is now a topical problem.The main part of such a terahertz source is a frequency synthesizer which is a system of successive multiplication (based on phase locking of oscillators of various ranges) of the frequency of a reference synthesizer operated, as a rule, in the centimeter-wave range. The submillimeter-wave synthesizer described for the first time in [9] and operated at frequencies of up to 840 GHz has 6 loops of frequency multiplication. Usually, planar semiconductor Schottky diodes are used as a nonlinear element in harmonic mixers of

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Pure Rotational Spectrum of HCN in the Terahertz Region: Use of a New Planar Schottky Diode Multiplier

Cited by 42 publications

References 12 publications

Gas‐Phase Detection of HSOH: Synthesis by Flash Vacuum Pyrolysis of Di‐tert‐butyl Sulfoxide and Rotational‐Torsional Spectrum

Gas‐Phase Detection of HSOH: Synthesis by Flash Vacuum Pyrolysis of Di‐tert‐butyl Sulfoxide and Rotational‐Torsional Spectrum

Broadband Terahertz Source Based on Photomixing in Laser-Assisted Field Emission with Clusters of Carbon Nanotubes

Development and design of a phase-locked loop in the subterahertz and terahertz ranges for a harmonic of the signal of a centimeter-wave synthesizer

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