Real-time ultrafast oscilloscope with a relativistic electron bunch train.

The deflection of charged particles is an intuitive way to visualize an electromagnetic oscillation of coherent light. Here, we present a real-time ultrafast oscilloscope for time-frozen visualization of a terahertz (THz) optical wave by probing light-driven motion of relativistic electrons. We found the unique condition of subwavelength metal slit waveguide for preserving the distortion-free optical waveform during its propagation. Momentary stamping of the wave, transversely travelling inside a metal slit, on an ultrashort wide electron bunch enables the single-shot recording of an ultrafast optical waveform. As a proof-of-concept experiment, we successfully demonstrated to capture the entire field oscillation of a THz pulse with a sampling rate of 75.7 TS/s. Owing to the use of transversely-wide and longitudinally-short electron bunch and transversely travelling wave, the proposed "single-shot oscilloscope" will open up new avenue for developing the real-time petahertz (PHz) metrology.

E. coli aggregation and impaired cell division after terahertz irradiation.

In this study we demonstrated that exposure of Escherichia coli (E. coli) to terahertz (THz) radiation resulted in a change in the activities of the tdcABCDEFGR and matA-F genes (signs of cell aggregation), gene yjjQ (signs of suppression of cell motility), dicABCF, FtsZ, and minCDE genes (signs of suppression of cell division), sfmACDHF genes (signs of adhesin synthesis), yjbEFGH and gfcA genes (signs of cell envelope stabilization). Moreover, THz radiation induced E. coli csg operon genes of amyloid biosynthesis. Electron microscopy revealed that the irradiated bacteria underwent increased aggregation; 20% of them formed bundle-like structures consisting of two to four pili clumped together. This could be the result of changes in the adhesive properties of the pili. We also found aberrations in cell wall structure in the middle part of the bacterial cell; these aberrations impaired the cell at the initial stages of division and resulted in accumulation of long rod-like cells. Overall, THz radiation was shown to have adverse effects on bacterial populations resulting in cells with abnormal morphology.

On species of the genus emMacrosaldula/em (Hemiptera: Heteroptera: Saldidae) of the Palaearctic Region, with description of emM. graziae/em sp. nov.

In this paper, we present new data on the genus Macrosaldula Leston Southwood, 1964 based on material held in the collections of the National Museum (Prague, Czech Republic) and the Zoological Institute of the Russian Academy of Sciences (St. Petersburg, Russia). Macrosaldula graziae sp. nov., from South Uzbekistan and Tajikistan, is described. Among the Central Asian species of the genus, it is close to M. tadzhika (Kiritshenko, 1912) by the presence of long erect setae on the body dorsum, but the latter species differs in the smaller body size, the presence of light spots on the corium, and in the structure of the male genitalia. In extremely dark specimens of M. jakowleffi (Reuter, 1891), the hemelytra are opaque, with short erect setae. Siberian M. rivularia (J. Sahlberg, 1878), M. simulans Cobben, 1985 and the Far Eastern M. koreana (Kiritshenko, 1912) and M. violacea Cobben, 1985 are distinguished from the new species by the short pubescence on the dorsum. We provide new distributional data for M. clavalis Cobben, 1985 (Georgia), M. jakowleffi (Reuter, 1891) (China: Xinjiang: Altai Mts.-first record), M. miyamotoi Cobben, 1985 (Japan: Honshu), M. nivalis (Lindberg, 1935) (Afghanistan-first record, Kyrgyzstan, Tajikistan), M. scotica (Curtis, 1835) (Georgia: Adzharia; Russia: Murmansk District), and M. tadzhika (Afghanistan-first record, Tajikistan, Uzbekistan). The record of M. scotica from Uzbekistan is disconsidered, and the two specimens are referred to M. graziae sp. nov.

Method for developing a sub-10 fs ultrafast electron diffraction technology.

The experimental observation of femtosecond dynamics in atoms and molecules by stroboscopic technologies utilizing x ray or electron flashes has attracted much attention and has rapidly developed. We propose a feasible ultrafast electron diffraction (UED) technology with high brightness and a sub-10 fs temporal resolution. We previously demonstrated a UED system with an overall temporal resolution of 31 fs by using an RF photoelectron gun and a 90° achromatic bending structure. This UED structure enabled a bunch duration of 25 fs and a low timing jitter of less than 10 fs while maintaining a high bunch charge of 0.6 pC. In this paper, we demonstrate a simple way to further compress the electron bunch duration to sub-10 fs based on installing an energy filter in the dispersion section of the achromatic bend. The energy filter removes the electrons belonging to nonlinear parts of the phase space. Through numerical simulations, we demonstrate that the electron bunches can be compressed, at the sample position, to a 6.2 fs (rms) duration for a 100 fC charge. This result suggests that the energy filtering approach is more viable and effective than complicated beam-shaping techniques that commonly handle the nonlinear distribution of the electron beam. Furthermore, a gas-filled hollow core fiber compressor and a Ti:sapphire amplifier are used to implement pump laser pulses of less than 5 fs (rms). Thus, we could present the full simulation results of a sub-10 fs UED, and we believe that it will be one of the technical prototypes to challenge the sub-fs time resolution.

Quasi-Talbot effect with vortex beams and formation of vortex beamlet arrays.

We study diffraction of Bessel vortex beams with topological charges of ±1 and ±2 and a wavelength of 130 µm on two-dimensional amplitude periodic gratings. Results of simulations and experiments at the Novosibirsk Free Electron Laser facility show that there appear periodic patterns in the planes corresponding to the classical main and fractional Talbot planes, but instead of self-images of the holes, there are observed periodic lattices of annular vortex microbeams with topological charges corresponding to the charge of the beam illuminating the grating. The ring diameters are the same for beams with different topological charges, but they are proportional to the grating period and inversely proportional to the diameter of the beam illuminating the grating.

THz-pump and X-ray-probe sources based on an electron linac.

We describe a compact THz-pump and X-ray-probe beamline, based on an electron linac, for ultrafast time-resolved diffraction applications. Two high-energy electron (γ > 50) bunches, 5 ns apart, impinge upon a single-foil or multifoil radiator and generate THz radiation and X-rays simultaneously. The THz pulse from the first bunch is synchronized to the X-ray beam of the second bunch by using an adjustable optical delay of a THz pulse. The peak power of THz radiation from the multifoil radiator is estimated to be 0.14 GW for a 200 pC well-optimized electron bunch. GEANT4 simulations show that a carbon foil with a thickness of 0.5-1.0 mm has the highest yield of 10-20 keV hard X-rays for a 25 MeV beam, which is approximately 103 photons/(keV pC-electrons) within a few degrees of the polar angle. A carbon multifoil radiator with 35 foils (25 µm thick each) can generate close to 103 hard X-rays/(keV pC-electrons) within a 2° acceptance angle. With 200 pC charge and a 100 Hz repetition rate, we can generate 107 X-rays per 1 keV energy bin per second or 105 X-rays per 1 keV energy bin per pulse. The longitudinal time profile of an X-ray pulse ranges from 400 to 600 fs depending on the acceptance angle. The broadening of the time duration of an X-ray pulse is observed owing to its diverging effect. A double-crystal monochromator will be used to select and transport the desired X-rays to the sample. The heating of the radiators by an electron beam is negligible because of the low beam current.

Contribution to the faunistics of shore bugs (Hemiptera: Heteroptera: Leptopodomorpha) in the Palaearctic Region and the Himalayas.

New distributional data on 33 species of the infraorder Leptopodomorpha (3 species of the family Leptopodidae and 30 species and subspecies of Saldidae) from the Palaearctic Region and Himalayas are provided. The following new or confirmed records are listed: Chartoscirta cocksii (Curtis, 1835) from Kosovo; Halosalda halophila (Jakovlev, 1876), Saldula amplicollis (Reuter, 1891) and Saldula xanthochila (Fieber, 1859) from Iran; Macrosaldula jakowleffi (Reuter, 1891) from Nepal and Pakistan; Macrosaldula scotica (Curtis, 1835) from Uzbekistan; Macrosaldula variabilis (Herrich-Schaeffer, 1835), Saldula lindskogi Vinokurov, 2004, Saldula opacula (Zetterstedt, 1838) from Afghanistan; Micracanthia ornatula (Reuter, 1881) from Oman; Saldula fucicola (J. Sahlberg, 1870) from Bosnia and Herzegovina and Bulgaria; Saldula lindbergi Lindskog, 1975 from Lebanon; Saldula melanoscela (Fieber, 1859) from Iran and Montenegro; Saldula palustris (Douglas, 1874) and Saldula pilosella hirsuta (Reuter, 1888) from Montenegro; Saldula orthochila (Fieber, 1859) from Afghanistan and Pakistan; Saldula pallipes (Fabricius, 1794) from Montenegro and Nepal; Saldula pilosella pilosella (Thomson, 1871) from Libya; and Saldula saltatoria (Linnaeus, 1758) from Iran and Nepal. A tabular checklist of Leptopodomorpha of Afghanistan, Iran and Pakistan is also provided.

Development of an S-band cavity-type beam position monitor for a high power THz free-electron laser.

A cavity-type beam position monitor (BPM) has been developed for a compact terahertz (THz) free-electron laser (FEL) system and ultra-short pulsed electron Linac system at the Korea Atomic Energy Research Institute (KAERI). Compared with other types of BPMs, the cavity-type BPM has higher sensitivity and faster response time even at low charge levels. When electron beam passes through the cavity-type BPM, it excites the dipole mode of the cavity of which amplitude depends linearly on the beam offset from the center of the cavity. Signals from the BPM were measured as a function of the beam offset by using an oscilloscope. The microtron accelerator for the KAERI THz FEL produces the electron beam with an energy of 6.5 MeV and pulse length of 5 µs with a micropulse of 10-20 ps at the frequency of 2.801 GHz. The macropulse beam current is 40 mA. Because the microtron provides multi-bunch system, output signal would be the superposition of each single bunch. So high output signal can be obtained from superposition of each single bunch. The designed position resolution of the cavity-type BPM in multi-bunch is submicron. Our cavity-type BPM is made of aluminum and vacuum can be maintained by indium sealing without brazing process, resulting in easy modification and cost saving. The resonance frequency of the cavity-type BPM is 2.803 GHz and the cavity-type BPM dimensions are 200 × 220 mm (length × height) with a pipe diameter of 38 mm. The measured position sensitivity was 6.19 (mV/mm)/mA and the measured isolation between the X and Y axis was -39 dB. By measuring the thermal noise of system, position resolution of the cavity-type BPM was estimated to be less than 1 µm. In this article, we present the test results of the S-band cavity-type BPM and prove the feasibility of the beam position measurement with high resolution using this device.

In vivo analysis of THz wave irradiation induced acute inflammatory response in skin by laser-scanning confocal microscopy.

The recent development of THz sources in a wide range of THz frequencies and power levels has led to greatly increased interest in potential biomedical applications such as cancer and burn wound diagnosis. However, despite its importance in realizing THz wave based applications, our knowledge of how THz wave irradiation can affect a live tissue at the cellular level is very limited. In this study, an acute inflammatory response caused by pulsed THz wave irradiation on the skin of a live mouse was analyzed at the cellular level using intravital laser-scanning confocal microscopy. Pulsed THz wave (2.7 THz, 4 µs pulsewidth, 61.4 µJ per pulse, 3Hz repetition), generated using compact FEL, was used to irradiate an anesthetized mouse's ear skin with an average power of 260 mW/cm(2) for 30 minutes using a high-precision focused THz wave irradiation setup. In contrast to in vitro analysis using cultured cells at similar power levels of CW THz wave irradiation, no temperature change at the surface of the ear skin was observed when skin was examined with an IR camera. To monitor any potential inflammatory response, resident neutrophils in the same area of ear skin were repeatedly visualized before and after THz wave irradiation using a custom-built laser-scanning confocal microscopy system optimized for in vivo visualization. While non-irradiated control skin area showed no changes in the number of resident neutrophils, a massive recruitment of newly infiltrated neutrophils was observed in the THz wave irradiated skin area after 6 hours, which suggests an induction of acute inflammatory response by the pulsed THz wave irradiation on the skin via a non-thermal process.

Generating high-power short terahertz electromagnetic pulses with a multifoil radiator.

We describe a multifoil cone radiator capable of generating high-field short terahertz pulses using short electron bunches. Round flat conducting foil plates with successively decreasing radii are stacked, forming a truncated cone with the z axis. The gaps between the foil plates are equal and filled with some dielectric (or vacuum). A short relativistic electron bunch propagates along the z axis. At sufficiently high particle energy, the energy losses and multiple scattering do not change the bunch shape significantly. When passing by each gap between the foil plates, the electron bunch emits some energy into the gap. Then, the radiation pulses propagate radially outward. For transverse electromagnetic waves with a longitudinal (along the z axis) electric field and an azimuthal magnetic field, there is no dispersion in these radial lines; therefore, the radiation pulses conserve their shapes (time dependence). At the outer surface of the cone, we have synchronous circular radiators. Their radiation field forms a conical wave. Ultrashort terahertz pulses with gigawatt-level peak power can be generated with this device.

Influence of intense THz radiation on spin state of photoswitchable compound Cu(hfac)2L(Pr).

The family of magnetoactive compounds Cu(hfac)(2)L(R) exhibits thermo- and photoswitching phenomena promising for various applications. Photoswitching of the Cu(hfac)(2)L(Pr) compound can be observed at temperatures below 20 K and is accompanied by transition to metastable structural state. Reverse conversion to stable structure could not be induced by light of near-IR-vis-UV regions up to date. The far-IR spectra of metastable and stable structural states are different and show characteristic absorption lines in the range of 170-240 cm(-1). These frequencies are accessible by NovoFEL - high-power THz free-electron laser user facility in Novosibirsk. We investigate selective influence of THz radiation on relaxation processes from metastable to stable structural state, which can be monitored by electron paramagnetic resonance (EPR). For this purpose, the experimental station based on X-band EPR spectrometer has been constructed by the THz beamline of NovoFEL and equipped with multimodal THz waveguide allowing to fed radiation directly into the EPR resonator. It has been found that irradiation of studied compound with high-power THz light causes significant but nondestructive increase of its temperature. Apart from this effect, no resonant influence of THz irradiation on relaxation processes has been observed. The experimental results have been rationalized taking into account vibrational relaxation times of the studied compound. Further experiments based on pulse heating by THz radiation have been proposed.

Studying the non-thermal effects of terahertz radiation on E. coli/pKatG-GFP biosensor cells.

Studies of the impact of terahertz radiation on living objects present a significant interest since its use for security systems is currently considered promising. We studied the non-thermal impact of terahertz radiation on E. coli/pKatG-gfp biosensor cells. The Novosibirsk free electron laser (NovoFEL), which currently has the world's highest average and peak power, was used as the source of terahertz radiation. We demonstrated that exposure to terahertz radiation at the wavelengths of 130, 150, and 200 µm and a power of 1.4 W/cm(2) induces changes in green fluorescent protein (GFP) fluorescence values and thus induces the expression of GFP in E. coli/pKatG-gfp biosensor cells. Possible mechanisms of the E. coli response to non-thermal exposure to terahertz radiation are discussed.

Two new species, new synonymies, and new records of Plant bugs (Hemiptera: Heteroptera: Miridae) from Northwestern China.

Two new species of Miridae, Myrmecophyes bykovi sp. nov. and Scirtetellus medvedevae sp. nov., are described from Xinjiang province of China. Illustrations of the male genitalia, tarsus, and pretarsus; photographs of the dorsal habitus; known hosts; and distributional records are provided for each species. Two new synonymies are established, viz. Chlainydatus laminatus Li & Liu, 2006 = Chlamydatus eurotiae Kerzhner, 1962; and Chlainydatus sichuanensis Li & Liu, 2006 = Chlamydatuspullus (Reuter, 1870). The following 13 species of Miridae are recorded for the first time from China: Camptotylus meyeri Frey-Gessner, 1863, Dicyphus testaceus Reuter, 1879, Liocoris tripustulatus (Fabricius, 1781), Monocris griseolus Putshkov, 1974, Myrmecophyes kiritshenkoi Horvith, 1927, Orthotylus melanotylus Kerzhner, 1962, Phytocoris incanus Fieber, 1864, Psallopsis haloxyli Putshkov, 1976, Psallopsis kallidiicola Konstantinov, 1997, Psallus anticus (Reuter, 1876), Scirtetellus seminitens Horvith, 1904, Tuponia (Chlorotuponia) loginovae Drapolyuk, 1982, and Tuponia (Chlorotuponia) cristifera Drapolyuk, 1982. Also, the following six species of plant bugs are new records for Xinjiang Province: Canptotylidea suturalis (Reuter, 1904), Chlamydatus eurotiae Kerzhner, 1962, Compsidolon punilun (Jakovlev, 1876), Excentricoris pictipes (Reuter, 1878), Glaucopteruin gobicum Kerzhner, 1984, Oncotylus vitticeps Reuter, 1879. Pherolepis aenescens (Reuter, 1901) is indicated for Xinjiang and Liaoning Provinces. Indication of Scirtetellus gudali Kiritshenko from Inner Mongolia (Bai et al. 2006) is considered erroneous.