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101.
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103.
采用太赫兹时域光谱(THz-TDS)测试和理论模拟相结合的方法,研究了组氨酸和精氨酸在THz波段的光谱特性.THz-TDS测试的有效光谱范围为0.2—2.8 THz,在该波段得到样品的特征吸收峰分别位于0.88,1.64,2.23 THz(组氨酸)和0.99,1.47,2.60 THz(精氨酸);运用Gaussian03半经验理论PM3和AM1算法,计算了两种分子在0.1—10.0 THz波段的振动吸收谱,结果表明它们在该波段均具有多个特征吸收,其中在0.2—2.8 THz波段的吸收峰位与实验吸收峰位相互对应并且符合较好;给出了与光谱特征吸收对应的分子振转模型,为认识分子对THz波的响应机制提供了帮助,也为分子鉴别及更宽有效光谱区的实验测试研究提供了科学依据.
关键词:
太赫兹(THz)
半经验理论
THz时域光谱
氨基酸 相似文献
104.
We offer an innovative optical material parameter extraction algorithm for Terahertz time-domain spectroscopy (THz-TDS). Unlike previously reported extraction algorithms in frequency domain, which have to be compromised between amplitude and phase, or the real part and imaginary part of the transfer function, we calculate material parameters by minimizing the difference between the measured sample waveform and the rebuilt one in time domain. The new method is effectively verified by different samples, and can be used either in transmission mode or in reflection mode for THz-TDS. 相似文献
105.
V. N. Dobrovolsky F. F. Sizov Y. E. Kamenev A. B. Smirnov 《Opto-Electronics Review》2008,16(2):172-178
A model of semiconductor hot electron bolometer (SHEB), in which electromagnetic radiation heats only electrons in narrow-gap
semiconductor without its lattice slow-response heating, is considered. Free carrier heating changes the generation-recombination
processes that are the reason of semiconductor resistance rise. It is estimated, that Hg0.8Cd0.2Te detector noise equivalent power (NEP) for mm and sub-mm radiation wavelength range can reach NEP ∼10−11 W at Δf = 1 Hz signal gain frequency bandwidth. Measurements performed at electromagnetic wave frequencies v = 36, 39, 55,
75 GHz, and at 0.89 and 1.58 THz too, with non-optimized Hg0.8Cd0.2Te antenna-coupled bolometer prototype confirmed the basic concept of SHEB. The experimental sensitivity Sv ∼2 V/W at T = 300 K and the calculated both Johnson-Nyquist and generation-recombination noise values gave estimation of
SHEB NEP ∼3.5 × 10−10 W at the band-width Δf = 1 Hz and v = 36 GHz. 相似文献
106.
P. Calvani S. Lupi M. Ortolani L. Baldassarre C. Mirri R. Sopracase U. Schade Y. Takano T. Tamegai 《Infrared Physics & Technology》2008,51(5):429-432
We show how coherent synchrotron radiation (CSR) allows one to measure the slight increase in the reflectivity of a BCS superconductor as it is cooled below Tc. In fact, by CSR coupled to a conventional interferometric apparatus, one can obtain a signal-to-noise ratio 103 in the sub-THz range. We apply this technique to the measurement of the optical gap in boron-doped diamond and in CaAlSi, a superconductor isostructural to MgB2. In the latter compound we are also able to determine a slight anisotropy between the gap in the hexagonal planes and that along the orthogonal c axis. 相似文献
107.
T. Idehara I. Ogawa La Agusu T. Kanemaki S. Mitsudo T. Saito T. Fujiwara H. Takahashi 《International Journal of Infrared and Millimeter Waves》2007,28(6):433-442
Gyrotron FU CW II with an 8 T liquid He free superconducting magnet, the second gyrotron of the THz Gyrotron FU CW Series,
has been constructed and the operation test was successfully carried out. It will be used for enhancing the sensitivity of
600 MHz proton-NMR by use of Dynamic Nuclear Polarization (DNP). The designed operation mode of the gyrotron is TE2,6 at the second harmonic. The corresponding frequency is 394.6 GHz. The real operation frequency is 394.3 GHz at TE06 mode, because of fabrication error of the diameter of the cavity. The operation is in complete CW at the output power of
around 30 W or higher at the TE06 cavity mode. There are many other operation modes at the fundamental and the second harmonic. Typical output power of the
fundamental and the second harmonic are higher than 100 W and 20 W, respectively. The highest frequency observed up to the
present is 443.5 GHz at the second harmonic operation of TE6,5 mode. The measured results are compared with the theoretical consideration. 相似文献
108.
Terahertz (THz) imaging which is a new technology for material classification and nondestructive detection has been extensively investigated in the past decade. The time-domain waveform acquired at each point of the object by using the THz time-domain spectroscopy contains much information about the object. Processing this waveform will present the characters of the object. Several methods are adopted to generate the image of the explosive samples and results are compared and discussed. Experiment results indicate that this new imaging technology can be used for explosive detection. 相似文献
109.
古新安 朱韦臻 罗志伟 ANGELUTS A A EVDOKIMOV M G NAZAROV M M SHKURINOV A P ANDREEV Y M LANSKII G V SHAIDUKO A V KOKH K A SVETLICHNYI V A 《中国光学》2012,5(1):57-63
从GaSe∶AgGaSe2熔体(质量掺杂浓度为10%)中生长的非线性光学晶体ε-GaSe∶Ag晶体(质量掺杂浓度≤0.04%)是一种非中心对称晶体,可用于相位匹配频率转换。Ag的掺入使GaSe晶体的显微硬度提高了30%,从而使其可以在任意方向上进行切割和抛光。本文研究了GaSe∶AgGaSe2晶体在可见、中红外及太赫兹波段的光学性能。实验证明:GaSe∶AgGaSe2晶体的吸收系数是纯GaSe晶体的2倍,其CO2激光倍频效率是ZnGeP2晶体的1.7倍。 相似文献
110.
The terahertz (THz) frequency radiation production as a result of nonlinear interaction of high intense laser beam with low density ripple in a magnetized plasma has been studied. If the appropriate phase matching conditions are satisfied and the frequency of the ripple is appropriate then this difference frequency can be brought in the THz range. Self focusing (filamentation) of a circularly polarized beam propagating along the direction of static magnetic field in plasma is first investigated within extended‐paraxial ray approximation. The beam gets focused when the initial power of the laser beam is greater than its critical power. Resulting localized beam couples with the pre‐existing density ripple to produce a nonlinear current driving the THz radiation. By changing the strength of the magnetic field, one can enhance or suppress the THz emission. The expressions for the laser beam width parameter, the electric field vector of the THz wave have been obtained. For typical laser beam and plasma parameters with the incident laser intensity ≈ 1014 W/cm2, laser beam radius (r0) = 50 μm, laser frequency (ω0) = 1.8848 × 1014rad/s, electron plasma (low density rippled) wave frequency (ω0) = 1.2848 × 1014 rad/s, plasma density (n0) = 5.025 × 1017cm–3, normalized ripple density amplitude (μ)=0.1, the produced THz emission can be at the level of Giga watt (GW) in power (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献