|   | 
Details
   web
Records
Author (up) Akhmadishina, K. F.; Bobrinetskiy, I. I.; Komarov, I. A.; Malovichko, A. M.; Nevolin, V. K.; Fedorov, G. E.; Golovin, A. V.; Zalevskiy, A. O.; Aidarkhanov, R. D.
Title Fast-response biological sensors based on single-layer carbon nanotubes modified with specific aptamers Type Journal Article
Year 2015 Publication Semicond. Abbreviated Journal Semicond.
Volume 49 Issue 13 Pages 1749-1753
Keywords carbon nanotubes, CNT detectors
Abstract The possibility of the fabrication of a fast-response biological sensor based on a composite of single-layer carbon nanotubes and aptamers for the specific detection of proteins is shown. The effect of modification of the surface of the carbon nanotubes on the selectivity and sensitivity of the sensors is investigated. It is shown that carboxylated nanotubes have a better selectivity for detecting thrombin.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1063-7826 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1783
Permanent link to this record
 

 
Author (up) Bandurin, D. A.; Gayduchenko, I.; Cao, Y.; Moskotin, M.; Principi, A.; Grigorieva, I. V.; Goltsman, G.; Fedorov, G.; Svintsov, D.
Title Dual origin of room temperature sub-terahertz photoresponse in graphene field effect transistors Type Journal Article
Year 2018 Publication Appl. Phys. Lett. Abbreviated Journal Appl. Phys. Lett.
Volume 112 Issue 14 Pages 141101 (1 to 5)
Keywords graphene field effect transistors, FET
Abstract Graphene is considered as a promising platform for detectors of high-frequency radiation up to the terahertz (THz) range due to its superior electron mobility. Previously, it has been shown that graphene field effect transistors (FETs) exhibit room temperature broadband photoresponse to incoming THz radiation, thanks to the thermoelectric and/or plasma wave rectification. Both effects exhibit similar functional dependences on the gate voltage, and therefore, it was difficult to disentangle these contributions in previous studies. In this letter, we report on combined experimental and theoretical studies of sub-THz response in graphene field-effect transistors analyzed at different temperatures. This temperature-dependent study allowed us to reveal the role of the photo-thermoelectric effect, p-n junction rectification, and plasmonic rectification in the sub-THz photoresponse of graphene FETs.

D.A.B. acknowledges the Leverhulme Trust for financial support. The work of D.S. was supported by Grant No. 16-19-10557 of the Russian Scientific Foundation (theoretical model). G.F., I.G., M.M., and G.G. acknowledge the Russian Science Foundation [Grant No. 14-19-01308 (MIET, cryostat upgrade) and Grant No. 17-72-30036, (MSPU, photoresponse measurements), the Ministry of Education and Science of the Russian Federation (Contract No. 14.B25.31.0007 (device fabrication) and Task No. 3.7328.2017/LS (NEP analyses)] and the Russian Foundation for Basic Research [Grant No. 15-02-07841 (device design)]. The authors are grateful to Professor M. S. Shur for helpful discussions.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0003-6951 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1309
Permanent link to this record
 

 
Author (up) Bandurin, D. A.; Svintsov, D.; Gayduchenko, I.; Xu, S. G.; Principi, A.; Moskotin, M.; Tretyakov, I.; Yagodkin, D.; Zhukov, S.; Taniguchi, T.; Watanabe, K.; Grigorieva, I. V.; Polini, M.; Goltsman, G. N.; Geim, A. K.; Fedorov, G.
Title Resonant terahertz detection using graphene plasmons Type Journal Article
Year 2018 Publication Nat. Commun. Abbreviated Journal Nat. Commun.
Volume 9 Issue Pages 5392 (1 to 8)
Keywords THz, graphene plasmons
Abstract Plasmons, collective oscillations of electron systems, can efficiently couple light and electric current, and thus can be used to create sub-wavelength photodetectors, radiation mixers, and on-chip spectrometers. Despite considerable effort, it has proven challenging to implement plasmonic devices operating at terahertz frequencies. The material capable to meet this challenge is graphene as it supports long-lived electrically tunable plasmons. Here we demonstrate plasmon-assisted resonant detection of terahertz radiation by antenna-coupled graphene transistors that act as both plasmonic Fabry-Perot cavities and rectifying elements. By varying the plasmon velocity using gate voltage, we tune our detectors between multiple resonant modes and exploit this functionality to measure plasmon wavelength and lifetime in bilayer graphene as well as to probe collective modes in its moire minibands. Our devices offer a convenient tool for further plasmonic research that is often exceedingly difficult under non-ambient conditions (e.g. cryogenic temperatures) and promise a viable route for various photonic applications.
Address Physics Department, Moscow State University of Education (MSPU), Moscow, Russian Federation, 119435. fedorov.ge@mipt.ru
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2041-1723 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1148
Permanent link to this record
 

 
Author (up) Belosevich, V. V.; Gayduchenko, I. A.; Titova, N. A.; Zhukova, E. S.; Goltsman, G. N.; Fedorov, G. E.; Silaev, A. A.
Title Response of carbon nanotube film transistor to the THz radiation Type Conference Article
Year 2018 Publication EPJ Web Conf. Abbreviated Journal EPJ Web Conf.
Volume 195 Issue Pages 05012 (1 to 2)
Keywords field-effect transistor, FET, carbon nanotube, CNT
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2100-014X ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1317
Permanent link to this record
 

 
Author (up) Dube, I.; Jiménez, D.; Fedorov, G.; Boyd, A.; Gayduchenko, I.; Paranjape, M.; Barbara, P.
Title Understanding the electrical response and sensing mechanism of carbon-nanotube-based gas sensors Type Journal Article
Year 2015 Publication Carbon Abbreviated Journal Carbon
Volume 87 Issue Pages 330-337
Keywords carbon nanotubes, CNT detectors, field effect transistors, FET
Abstract Gas sensors based on carbon nanotube field effect transistors (CNFETs) have outstanding sensitivity compared to existing technologies. However, the lack of understanding of the sensing mechanism has greatly hindered progress on calibration standards and customization of these nano-sensors. Calibration requires identifying fundamental transistor parameters and establishing how they vary in the presence of a gas. This work focuses on modeling the electrical response of CNTFETs in the presence of oxidizing (NO2) and reducing (NH3) gases and determining how the transistor characteristics are affected by gas-induced changes of contact properties, such as the Schottky barrier height and width, and by the doping level of the nanotube. From the theoretical fits of the experimental transfer characteristics at different concentrations of NO2 and NH3, we find that the CNTFET response can be modeled by introducing changes in the Schottky barrier height. These changes are directly related to the changes in the metal work function of the electrodes that we determine experimentally, independently, with a Kelvin probe. Our analysis yields a direct correlation between the ON – current and the changes in the electrode metal work function. Doping due to molecules adsorbed at the carbon-nanotube/metal interface also affects the transfer characteristics.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0008-6223 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1778
Permanent link to this record
 

 
Author (up) Eletskii, A. V.; Sarychev, A. K.; Boginskaya, I. A.; Bocharov, G. S.; Gaiduchenko, I. A.; Egin, M. S.; Ivanov, A. V.; Kurochkin, I. N.; Ryzhikov, I. A.; Fedorov, G. E.
Title Amplification of a Raman scattering signal by carbon nanotubes Type Journal Article
Year 2018 Publication Dokl. Phys. Abbreviated Journal Dokl. Phys.
Volume 63 Issue 12 Pages 496-498
Keywords carbon nanotubes, CNT, Raman scattering, RLS
Abstract The effect of Raman scattering (RLS) signal amplification by carbon nanotubes (CNTs) was studied. Single-layered nanotubes were synthesized by the chemical vapor deposition (CVD) method using methane as a carbon-containing gas. The object of study used was water, the Raman spectrum of which is rather well known. Amplification of the Raman scattering signal by several hundred percent was attained in our work. The maximum amplification of a Raman scattering signal was shown to be achieved at an optimal density of nanotubes on a substrate. This effect was due to the scattering and screening of plasmons excited in CNTs by neighboring nanotubes. The amplification mechanism and the possibilities of optimization for this effect were discussed on the basis of the theory of plasmon resonance in carbon nanotubes.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1028-3358 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1775
Permanent link to this record
 

 
Author (up) Emelianov, A. V.; Nekrasov, N. P.; Moskotin, M. V.; Fedorov, G. E.; Otero, N.; Romero, P. M.; Nevolin, V. K.; Afinogenov, B. I.; Nasibulin, A. G.; Bobrinetskiy, I. I.
Title Individual SWCNT transistor with photosensitive planar junction induced by two‐photon oxidation Type Journal Article
Year 2021 Publication Adv. Electron. Mater. Abbreviated Journal Adv. Electron. Mater.
Volume 7 Issue 3 Pages 2000872
Keywords SWCNT transistors
Abstract The fabrication of planar junctions in carbon nanomaterials is a promising way to increase the optical sensitivity of optoelectronic nanometer-scale devices in photonic connections, sensors, and photovoltaics. Utilizing a unique lithography approach based on direct femtosecond laser processing, a fast and easy technique for modification of single-walled carbon nanotube (SWCNT) optoelectronic properties through localized two-photon oxidation is developed. It results in a novel approach of quasimetallic to semiconducting nanotube conversion so that metal/semiconductor planar junction is formed via local laser patterning. The fabricated planar junction in the field-effect transistors based on individual SWCNT drastically increases the photoresponse of such devices. The broadband photoresponsivity of the two-photon oxidized structures reaches the value of 2 × 107 A W−1 per single SWCNT at 1 V bias voltage. The SWCNT-based transistors with induced metal/semiconductor planar junction can be applied to detect extremely small light intensities with high spatial resolution in photovoltaics, integrated circuits, and telecommunication applications.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2199-160X ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1843
Permanent link to this record
 

 
Author (up) Fedorov, G. E.; Gaiduchenko, I. A.; Golikov, A. D.; Rybin, M. G.; Obraztsova, E. D.; Voronov, B. M.; Coquillat, D.; Diakonova, N.; Knap, W.; Goltsman, G. N.; Samartsev, V. V.; Vinogradov, E. A.; Naumov, A. V.; Karimullin, K. R.
Title Response of graphene based gated nanodevices exposed to THz radiation Type Conference Article
Year 2015 Publication EPJ Web of Conferences Abbreviated Journal EPJ Web of Conferences
Volume 103 Issue Pages 10003 (1 to 2)
Keywords graphene field-effect transistor, FET
Abstract In this work we report on the response of asymmetric graphene based devices to subterahertz and terahertz radiation. Our devices are made in a configuration of a field-effect transistor with conduction channel between the source and drain electrodes formed with a CVD-grown graphene. The radiation is coupled through a spiral antenna to source and top gate electrodes. Room temperature responsivity of our devices is close to the values that are attractive for commercial applications. Further optimization of the device configuration may result in appearance of novel terahertz radiation detectors.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2100-014X ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1350
Permanent link to this record
 

 
Author (up) Fedorov, G. E.; Stepanova, T. S.; Gazaliev, A. S.; Gaiduchenko, I. A.; Kaurova, N. S.; Voronov, B. M.; Goltzman, G. N.
Title Asymmetric devices based on carbon nanotubes for terahertz-range radiation detection Type Journal Article
Year 2016 Publication Semicond. Abbreviated Journal Semicond.
Volume 50 Issue 12 Pages 1600-1603
Keywords carbon nanotubes, CNT detectors
Abstract Various asymmetric detecting devices based on carbon nanotubes (CNTs) are studied. The asymmetry is understood as inhomogeneous properties along the conducting channel. In the first type of devices, an inhomogeneous morphology of the CNT grid is used. In the second type of devices, metals with highly varying work functions are used as the contact material. The relation between the sensitivity and detector configuration is analyzed. Based on the data obtained, approaches to the development of an efficient detector of terahertz radiation, based on carbon nanotubes are proposed.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1063-7826 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1776
Permanent link to this record
 

 
Author (up) Fedorov, G.; Gayduchenko, I.; Titova, N.; Gazaliev, A.; Moskotin, M.; Kaurova, N.; Voronov, B.; Goltsman, G.
Title Carbon nanotube based schottky diodes as uncooled terahertz radiation detectors Type Journal Article
Year 2018 Publication Phys. Status Solidi B Abbreviated Journal Phys. Status Solidi B
Volume 255 Issue 1 Pages 1700227 (1 to 6)
Keywords carbon nanotube schottky diodes, CNT
Abstract Despite the intensive development of the terahertz technologies in the last decade, there is still a shortage of efficient room‐temperature radiation detectors. Carbon nanotubes (CNTs) are considered as a very promising material possessing many of the features peculiar for graphene (suppression of backscattering, high mobility, etc.) combined with a bandgap in the carrier spectrum. In this paper, we investigate the possibility to incorporate individual CNTs into devices that are similar to Schottky diodes. The latter is currently used to detect radiation with a frequency up to 50 GHz. We report results obtained with semiconducting (bandgap of about 0.5 eV) and quasi‐metallic (bandgap of few meV) single‐walled carbon nanotubes (SWNTs). Semiconducting CNTs show better performance up to 300 GHz with responsivity up to 100 V W−1, while quasi‐metallic CNTs are shown to operate up to 2.5 THz.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0370-1972 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1321
Permanent link to this record
 

 
Author (up) Fedorov, G.; Gayduchenko, I.; Titova, N.; Moskotin, M.; Obraztsova, E.; Rybin, M.; Goltsman, G.
Title Graphene-based lateral Schottky diodes for detecting terahertz radiation Type Conference Article
Year 2018 Publication Proc. Optical Sensing and Detection V Abbreviated Journal Proc. Optical Sensing and Detection V
Volume 10680 Issue Pages 30-39
Keywords graphene, terahertz radiation, detectors, Schottky diodes, carbon nanotubes, plasma waves
Abstract Demand for efficient terahertz radiation detectors resulted in intensive study of the carbon nanostructures as possible solution for that problem. In this work we investigate the response to sub-terahertz radiation of graphene field effect transistors of two configurations. The devices of the first type are based on single layer CVD graphene with asymmetric source and drain (vanadium and gold) contacts and operate as lateral Schottky diodes (LSD). The devices of the second type are made in so-called Dyakonov-Shur configuration in which the radiation is coupled through a spiral antenna to source and top electrodes. We show that at 300 K the LSD detector exhibit the room-temperature responsivity from R = 15 V/W at f= 129 GHz to R = 3 V/W at f = 450 GHz. The DS detector responsivity is markedly lower (2 V/W) and practically frequency independent in the investigated range. We find that at low temperatures (77K) the graphene lateral Schottky diodes responsivity rises with the increasing frequency of the incident sub-THz radiation. We interpret this result as a manifestation of a plasmonic effect in the devices with the relatively long plasmonic wavelengths. The obtained data allows for determination of the most promising directions of development of the technology of nanocarbon structures for the detection of THz radiation.
Address
Corporate Author Thesis
Publisher Spie Place of Publication Editor Berghmans, F.; Mignani, A.G.
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number 10.1117/12.2307020 Serial 1306
Permanent link to this record
 

 
Author (up) Fedorov, G.; Kardakova, A.; Gayduchenko, I.; Charayev, I.; Voronov, B.M.; Finkel, M.; Klapwijk, T.M.; Morozov, S.; Presniakov, M.; Bobrinetskiy, I.; Ibragimov, R.; Goltsman, G.
Title Photothermoelectric response in asymmetric carbon nanotube devices exposed to sub-terahertz radiation Type Journal Article
Year 2013 Publication Appl. Phys. Lett. Abbreviated Journal Appl. Phys. Lett.
Volume 103 Issue 18 Pages 181121 (1 to 5)
Keywords carbon nanotubes, CNT, THz radiation, SiO2 substrate
Abstract We report on the voltage response of carbon nanotube devices to sub-terahertz (THz) radiation. The devices contain carbon nanotubes (CNTs), which are over their length partially suspended and partially Van der Waals bonded to a SiO2 substrate, causing a difference in thermal contact. We observe a DC voltage upon exposure to 140 GHz radiation. Based on the observed gate voltage and power dependence, at different temperatures, we argue that the observed signal is both thermal and photovoltaic. The room temperature responsivity in the microwave to THz range exceeds that of CNT based devices reported before. Authors thank Professor P. Barbara for providing the catalyst for CNT growth and Dr. N. Chumakov and V. Rylkov for stimulating discussions. The work was supported by the RFBR (Grant No. 12-02-01291-a) and by the Ministry of Education and Science of the Russian Federation (Contract No. 14.B25.31.0007). G.F. acknowledges support of the RFBR grant 12-02-01005-a.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0003-6951 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1171
Permanent link to this record
 

 
Author (up) Fedorov, G.; Kardakova, A.; Gayduchenko, I.; Voronov, B. M.; Finkel, M.; Klapwijk, T. M.; Goltsman, G.
Title Photothermoelectric response in asymmetric carbon nanotube devices exposed to sub-THz radiation Type Abstract
Year 2014 Publication Proc. 25th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 25th Int. Symp. Space Terahertz Technol.
Volume Issue Pages 71
Keywords carbon nanotubes, CNT
Abstract This work reports on the voltage response of asymmetric carbon nanotube devices to sub-THz radiation at the frequency of 140 GHz. The devices contain CNT’s, which are over their length partially suspended and partially Van der Waals bonded to a SiO 2 substrate, causing a difference in thermal contact. Different heat sinking of CNTs by source and drain gives rise to temperature gradient and consequent thermoelectric power (TEP) as such a device is exposed to the sub-THz radiation. Sign of the DC signal, its power and gate voltage dependence observed at room temperature are consistent with this scenario. At liquid helium temperature the observed response is more complex. DC voltage signal of an opposite sign is observed in a narrow range of gate voltages at low temperatures and under low radiation power. We argue that this may indicate a true photovoltaic response from small gap (less than 10meV) CNT’s, an effect never reported before. While it is not clear if the observed effects can be used to develop efficient THz detectors we note that the responsivity of our devices exceeds that of CNT based devices in microwave or THz range reported before at room temperature. Besides at 4.2 K notable increase of the sample conductance (at least four-fold) is observed. Our recent results with asymmetric carbon nanotube devices response to THz radiation (2.5 THz) will also be presented.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1361
Permanent link to this record
 

 
Author (up) Florya, I. N.; Korneeva, Y. P.; Sidorova, M. V.; Golikov, A. D.; Gaiduchenko, I. A.; Fedorov, G. E.; Korneev, A. A.; Voronov, B. M.; Goltsman, G. N.; Samartsev, V. V.; Vinogradov, E. A.; Naumov, A. V.; Karimullin, K. R.
Title Energy relaxtation and hot spot formation in superconducting single photon detectors SSPDs Type Conference Article
Year 2015 Publication EPJ Web of Conferences Abbreviated Journal EPJ Web of Conferences
Volume 103 Issue Pages 10004 (1 to 2)
Keywords SSPD, SNSPD
Abstract We have studied the mechanism of energy relaxation and resistive state formation after absorption of a single photon for different wavelengths and materials of single photon detectors. Our results are in good agreement with the hot spot model.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2100-014X ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1351
Permanent link to this record
 

 
Author (up) Gayduchenko, I. A.; Fedorov, G. E.; Ibragimov, R. A.; Stepanova, T. S.; Gazaliev, A. S.; Vysochanskiy, N. A.; Bobrov, Y. A.; Malovichko, A. M.; Sosnin, I. M.; Bobrinetskiy, I. I.
Title Synthesis of single-walled carbon nanotube networks using monodisperse metallic nanocatalysts encapsulated in reverse micelles Type Journal Article
Year 2016 Publication Chem. Ind. Belgrade Abbreviated Journal Chem. Ind. Belgrade
Volume 70 Issue 1 Pages 1-8
Keywords carbon nanotubes, CNT, reverse micelles
Abstract We report on a method of synthesis of single-walled carbon nanotubes percolated networks on silicon dioxide substrates using monodisperse Co and Ni catalyst. The catalytic nanoparticles were obtained by modified method of reverse micelles of bis-(2-ethylhexyl) sulfosuccinate sodium in isooctane solution that provides the nanoparticle size control in range of 1 to 5 nm. The metallic nanoparticles of Ni and Co were characterized using transmission electron microscopy (TEM) and atomic-force microscopy (AFM). Carbon nanotubes were synthesized by chemical vapor deposition of CH4/H2 composition at temperature 1000 °С on catalysts pre-deposited on silicon dioxide substrate. Before temperature treatment during the carbon nanotube synthesis most of the catalyst material agglomerates due to magnetic forces while during the nanotube growth disintegrates into the separate nanoparticles with narrow diameter distribution. The formed nanotube networks were characterized using AFM, scanning electron microscopy (SEM) and Raman spectroscopy. We find that the nanotubes are mainly single-walled carbon nanotubes with high structural perfection up to 200 μm long with diameters from 1.3 to 1.7 nm consistent with catalyst nanoparticles diameter distribution and independent of its material.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0367-598X ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1779
Permanent link to this record