Toward highly stable Terahertz Coherent Synchrotron Radiation at the synchrotron SOLEIL

The rotational spectrum of propynal in the 250–700 GHz range using coherent synchrotron radiation Fourier transform spectrometry

“…The flux of this emission between 250 and 750 GHz (about 0.4 to 1.2 mm wavelength) is advantageous for performing broad band interferometric spectroscopy measurements (here about nine hours). For high resolution measurements, (here •30 MHz resolution) the signal-to-noise has been optimized through minimizing the source instabilities [14,16,17]. These optimal conditions allowing for an intense emission over a wide frequency range are found for a momentum compaction factor: α = α 0 /25 (with α 0 the nominal compaction factor) , corresponding to a theoretical bunch length at zero current of around 3 ps (1 mm), and a current per bunch of 70µA.…”

“…The synchrotron provides a source of infrared radiation that combines the advantages of a high brilliance and a wide spectral coverage [10 and reference therein]. To enhance its intensity in the THz range, a number of synchrotron radiation facilities around the world have studied the production of Coherent Synchrotron Radiation (CSR) obtained by reducing the bunch length so that it becomes comparable to the emitted wavelength [11][12][13][14][15][16][17]. Although this operation mode allows a large flux enhancement in the THz range (•10 10 4 ), the interaction of the electrons with their own electromagnetic field causes a microstructure (microbunching) in the electron bunch, resulting in bursts of THz radiation and with accompanying source instabilities [14].…”

“…For high resolution measurements, the use of CSR can be greatly hampered by these micro-bunching instabilities [10]. Recent developments at SOLEIL, however, demonstrated the potential advantages of CSR (brightness, stability, small beam divergence) which improve the S/N allowing the observation of weak bands even at high resolution [16,17]. Even though the ultimate available resolution (20 -30 MHz) using this technique is far from the sub-MHz resolution of the millimeter wave monochromatic scanning set-up, such studies present complementary properties: the whole spectral range is measured simultaneously, which is useful for the study of reactive species, the line intensities are easier to extract and the large number of lines recorded is advantageous in obtaining accurate constants.…”

Cross-Correlation of THz Pulses from the Electron Storage Ring BESSY II

“…More than fifteen years have passed since it was proven that CSR is a suitable source for diffraction-limited Fourier transform spectroscopy [8] and the first successful scientific experiment using THz radiation from short electron bunches was performed [9]. The low α technology is now becoming available at several storage rings worldwide (e.g., [10][11][12][13][14][15]) and this powerful broadband source allows for many scientific experiments [16] including THz-electron paramagnetic resonance (EPR) [17] and high-resolution spectroscopy with THz frequency combs [18]. Currently, storage rings offer to users the low α mode at reduced currents stored.…”