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

“…The two highest frequency lines of each isotopomer near 1.9 THz were measured with an accuracy of about 30 kHz, by using the frequency-stabilized Cologne laser sideband spectrometer. A detailed description will be found elsewhere (7,8). The two new data sets were fit to the conventional Hamiltonian of a linear molecule with the rotational and centrifugal distortion constants B, D, and H as summarized in Table 3.…”

“…In this study we report Doppler-limited, highly accurate measurements of the rotational spectrum up to 2 THz. By employing different frequency-generating techniques such as BWOs as fundamental frequency sources (5), frequency multipliers pumped by BWOs (6), and a frequency-stabilized laser sideband system with the use of BWOs for generating the sidebands (7,8), we have essentially opened the terahertz region for broadband scanning spectroscopy with an achievable absolute accuracy of about Ϯ1 kHz in the best of cases.…”

Pure Rotational Spectrum of Ethylenimine at 1.85 THz

“…More recently, we extended our investigations of ethylenimine into the terahertz regime that emphasize the sensitivity, accuracy obtainable, and broadband scanning abilities of the Cologne sideband spectrometer for terahertz applications (COSSTA) (4,5). Terahertz sideband radiation is generated by mixing the output of a frequency-stabilized FIR ring laser with that of a phase-stabilized backward-wave oscillator (BWO, Istok Research and Production Company, Moscow region, Russia) (6) as sources and a magnetically tuned, liquid-He-cooled InSb hot-electron bolometer as detector.…”

Quantum cascade laser-pumped terahertz molecular lasers: frequency noise and phase-locking using a 1560 nm frequency comb

“…S5). We also demonstrated that, should these values not be enough, QCL's pumped MLs can be phase-locked to more stable oscillators rather straightforwardly by controlling the QCL current, compared to CO2-pumped MLs, where phase-or frequency-locking requires a feedback on the cavity-length [27,[44][45][46]. In these experiments, the harmonic of the repetition rate of a custom-made, 1560nm, harmonically mode-locked FC has been used as reference oscillator.…”