The optical property and spectroscopy of selected kinds of lubricating oil are studied based on the terahertz time-domain spectroscopy (THz-TDS) in the spectral range of 0.3-1.6 THz. The samples are classified by thei...The optical property and spectroscopy of selected kinds of lubricating oil are studied based on the terahertz time-domain spectroscopy (THz-TDS) in the spectral range of 0.3-1.6 THz. The samples are classified by their characteristics via the near-infrared spectrum. The experimental results reveal that lubricating oil is more sensitive in the range of terahertz than in the near-infrared,and the specific kinds of lubricating oil can be identified according to their different spectral features in the terahertz range. The THz-TDS technology applied to lubricating oil analysis has potentially significant impact on the petroleum field.展开更多
The optical characteristics of four kinds of amino acids (tyrosine, arginine, histidine and glutamine) filled with nitrogen at room temperature were studied by THz time-domain spectroscopy (THz-TDS). Well-resolved abs...The optical characteristics of four kinds of amino acids (tyrosine, arginine, histidine and glutamine) filled with nitrogen at room temperature were studied by THz time-domain spectroscopy (THz-TDS). Well-resolved absorption and refractive spectrums between 0.1 and 2.8 THz were obtained based on the physical model for extract-ing the optical parameters of materials in THz range. The results not only fill up the spectra gap of amino acids in far-infrared range, supply data for amino acid molecular identification and conformation analysis, but also demon-strate significantly potential to promote the research and application of biological materials in bio-chemical and medical fields by THz-TDS.展开更多
Dear Editors, Terahertz technology has been applied in many fields [1-3]. The protection and restoration of historical relics and cul- tural heritage, which is a new application area of terahertz technology, have been...Dear Editors, Terahertz technology has been applied in many fields [1-3]. The protection and restoration of historical relics and cul- tural heritage, which is a new application area of terahertz technology, have been attracting much attention recently [4,5] because of its social significance and market prospects The most important premise is to obtain information of the cultural relics without damaging them again. Therefore the appropriate non-destructively testing methods are urgently needed in this area. Terahertz （THz） wave bridges the gap between microwave and infrared waves.展开更多
Characteristic spectra in the 0.5-2.5 terahertz (THz) range of three commercial derv fuel oils have been obtained using THz time-domain spectroscopy and calculated using density functional theory.The simulated results...Characteristic spectra in the 0.5-2.5 terahertz (THz) range of three commercial derv fuel oils have been obtained using THz time-domain spectroscopy and calculated using density functional theory.The simulated results and experimental absorption curves suggest that the skeleton vibration is predominant in the THz region,and the absorption bumps of diesels are a superposition of various components.The investigation demonstrates that different diesels can be distinguished using THz time-domain spectroscopy and THz technology is a promising method to detect the composition and properties of diesels via chemical analysis.展开更多
Structures consisting of a planar array of subwavelength metallic bars fabricated on a dielectric substrate are theoretically investigated in order to rotate the polarization of a normally incident terahertz wave in t...Structures consisting of a planar array of subwavelength metallic bars fabricated on a dielectric substrate are theoretically investigated in order to rotate the polarization of a normally incident terahertz wave in the resonance frequency band.We attribute this phenomenon to one component of the terahertz electric field parallel to inclined metallic bars which is reflected strongly due to the terahertz re-radiation from accelerated electrons in the metallic bars,while the other component perpendicular to the bars transmits almost entirely through the structures.By theoretical analysis,we obtain the transmitted-terahertz components polarized in the x-and y-directions,respectively.Further studies indicate polarization of a terahertz wave can be rotated within two specific frequency bands when the terahertz impinges on the double-bar sample.展开更多
The carrier dynamics and terahertz photoconductivity in the n-type silicon (n-Si) as well as in the p-type Silicon (p-Si) have been investigated by using femtosecond pump-terahertz probe technique. The measurements sh...The carrier dynamics and terahertz photoconductivity in the n-type silicon (n-Si) as well as in the p-type Silicon (p-Si) have been investigated by using femtosecond pump-terahertz probe technique. The measurements show that the relative change of terahertz transmission of p-Si at low pump power is slightly smaller than that of n-Si,due to the lower carrier density induced by the recombination of original holes in the p-type material and the photogenerated electrons. At high pump power,the bigger change of terahertz transmission of p-Si originates from the greater mobility of the carriers compared to n-Si. The transient photoconductivities are calculated and fit well with the Drude-Smith model,showing that the mobility of the photogenerated carriers decreases with the increasing pump power. The obtained results indicate that femtosecond pump-terahertz probe technique is a promising method to investigate the carrier dynamics of semiconductors.展开更多
基金Supported by the Program for New Century Excellent Talents in University (Grant No. NCET-08-0841)the National Natural Science Foundation of China (Grant Nos. 50672132, 60778034, and 60877038)+3 种基金the Key Project of Chinese Ministry of Education (Grant No. 107020)the Beijng Natural Science Foundation (Grant No. 4082026)the Research Fund for the Doctoral Program of Higher Education (Grant No. 200804250006)the State Key Laboratory of Heavy Oil Processing, China University Of Petroleum (Grant No. 2008-14)
文摘The optical property and spectroscopy of selected kinds of lubricating oil are studied based on the terahertz time-domain spectroscopy (THz-TDS) in the spectral range of 0.3-1.6 THz. The samples are classified by their characteristics via the near-infrared spectrum. The experimental results reveal that lubricating oil is more sensitive in the range of terahertz than in the near-infrared,and the specific kinds of lubricating oil can be identified according to their different spectral features in the terahertz range. The THz-TDS technology applied to lubricating oil analysis has potentially significant impact on the petroleum field.
文摘The optical characteristics of four kinds of amino acids (tyrosine, arginine, histidine and glutamine) filled with nitrogen at room temperature were studied by THz time-domain spectroscopy (THz-TDS). Well-resolved absorption and refractive spectrums between 0.1 and 2.8 THz were obtained based on the physical model for extract-ing the optical parameters of materials in THz range. The results not only fill up the spectra gap of amino acids in far-infrared range, supply data for amino acid molecular identification and conformation analysis, but also demon-strate significantly potential to promote the research and application of biological materials in bio-chemical and medical fields by THz-TDS.
基金supported by the National Natural Science Foundation of China(Grant Nos.11204191 and 11574408)the National Instrumentation Program(Grant No.2012YQ140005)Beijing Science and Technology Project(Grant No.D151100006015002)
文摘Dear Editors, Terahertz technology has been applied in many fields [1-3]. The protection and restoration of historical relics and cul- tural heritage, which is a new application area of terahertz technology, have been attracting much attention recently [4,5] because of its social significance and market prospects The most important premise is to obtain information of the cultural relics without damaging them again. Therefore the appropriate non-destructively testing methods are urgently needed in this area. Terahertz （THz） wave bridges the gap between microwave and infrared waves.
基金supported by the Program for New Century Excellent Talents in Universitythe National Natural Science Foundation of China+2 种基金the Research Fund for the Doctoral Program of Higher Educationthe State Key Laboratory of Heavy Oil Processing,China University of PetroleumForesight Fund Program from China University of Petroleum (Beijing)
文摘Characteristic spectra in the 0.5-2.5 terahertz (THz) range of three commercial derv fuel oils have been obtained using THz time-domain spectroscopy and calculated using density functional theory.The simulated results and experimental absorption curves suggest that the skeleton vibration is predominant in the THz region,and the absorption bumps of diesels are a superposition of various components.The investigation demonstrates that different diesels can be distinguished using THz time-domain spectroscopy and THz technology is a promising method to detect the composition and properties of diesels via chemical analysis.
基金supported by the National Natural Science Foundation of China(Grant Nos.10804077,10904098 and 11011120242)the National Basic Research Program of China(Grant No.2007CB310408)+2 种基金the Ministry of Education Key Project(Grant No.210002)Beijing Municipal Commission of Education(Grant Nos.KM200910028006 and KM201110028004)Beijing Nova Program and Funding Project for Academic Human Resources Development in Institutions of Higher Learning Under the Jurisdiction of Beijing Municipality
文摘Structures consisting of a planar array of subwavelength metallic bars fabricated on a dielectric substrate are theoretically investigated in order to rotate the polarization of a normally incident terahertz wave in the resonance frequency band.We attribute this phenomenon to one component of the terahertz electric field parallel to inclined metallic bars which is reflected strongly due to the terahertz re-radiation from accelerated electrons in the metallic bars,while the other component perpendicular to the bars transmits almost entirely through the structures.By theoretical analysis,we obtain the transmitted-terahertz components polarized in the x-and y-directions,respectively.Further studies indicate polarization of a terahertz wave can be rotated within two specific frequency bands when the terahertz impinges on the double-bar sample.
基金Supported by the National Basic Research Program of China (Grant Nos. 2007CB310408 and 2006CB302901)the National Natural Science Foundation of China (Grant No. 10804077)+2 种基金Beijing Municipal Commission of Education (Grant No. KM200910028006)Funding Project for Academic Human Resources Development in Institutions of Higher Learning Under the Jurisdiction of Beijing Municipalitythe State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences
文摘The carrier dynamics and terahertz photoconductivity in the n-type silicon (n-Si) as well as in the p-type Silicon (p-Si) have been investigated by using femtosecond pump-terahertz probe technique. The measurements show that the relative change of terahertz transmission of p-Si at low pump power is slightly smaller than that of n-Si,due to the lower carrier density induced by the recombination of original holes in the p-type material and the photogenerated electrons. At high pump power,the bigger change of terahertz transmission of p-Si originates from the greater mobility of the carriers compared to n-Si. The transient photoconductivities are calculated and fit well with the Drude-Smith model,showing that the mobility of the photogenerated carriers decreases with the increasing pump power. The obtained results indicate that femtosecond pump-terahertz probe technique is a promising method to investigate the carrier dynamics of semiconductors.
