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通过HCN信号的测量与处理来获得等离子体电子密度。采用硬件相位差计获取HT-7装置中原始HCN信号,根据对该信号特点的分析, 设计出信号去零漂、信号翻转、基于模糊逻辑的去噪处理算法。在HT-7装置实验中,使用该算法获得了较高精度的低噪音等离子体电子密度。     

Influences on HCN laser frequency by the parameters of the laser

The influences on HCN laser frequency by the parameters of the laser have been discussed theoretically and experimentally. The frequency variations of the HCN laser versus discharge current and gas pressure have been measured to be 2.9 kHz/mA and 8.1 kHz/mtorr respectively. The experimental results have been explained theoretically.     

The vacuum ultraviolet spectra of HCN,C2N2, and CH3CN

Quantitative vacuum ultraviolet absorption spectra for HCN, C₂N₂, and CH₃CN have been obtained over the wavelength range 60 nm ? λ ? 160 nm. Where comparison is possible, our measurements of the absorption coefficients for HCN and C₂N₂ are consistent with previous studies. Because of the superior resolution of this work (0.05 nm), vibrational assignments in the valence and Rydberg transitions of HCN have been extended while higher members of the Rydberg series in CH₃CN have been identified.     

Rydberg states of HCN observed by electron impact spectroscopy

The electron energy loss spectrum of HCN has been determined in the energy region 8–13.6 eV at impact energies of 100, 50 and 30 eV. It is shown that energy loss spectra of HCN at intermediate impact energies can be satisfactorily analysed unlike the diffuse unassigned optical absorption spectra that have previously been reported. Rydberg series have been assigned using term values and quantum defects together with ionization potentials obtained by photoelectron spectroscopy.     

Excitation,inversion, and relaxation mechanisms of the HCN FIR discharge laser

Millimeter/submillimeter rotational absorption spectroscopy has been used as a diagnostic probe of a cw HCN discharge laser. This sensitive technique allowed in situ absolute population measurements of a number of vibrational states of HCN (including the upper lasing state) and other pertinent molecules. This unique set of data, which was obtained under a variety of discharge and laser conditions, is directly related to excitation, inversion, and relaxation processes. Along with elucidating several fundamental aspects of inversion and relaxation these results also strongly indicate that the primary laser excitation mechanism is near-resonant energy transfer from vibrationally excited nitrogen, N₂ (v=1), to the fundamental symmetric stretching mode of hydrogen cyanide, HCN(100), and subsequent thermal population exchange between HCN (100) and the upper laser state, HCN (110).Work supported by ARO Contract DAAG-29-83-K-0078     

Photoelectron and electron impact spectrum of HCN

The electronic structures of HCN and DCN have been determined by examining high resolution He(I) photelectron spectra of HCN and DCN, He(II) photoelectron spectrum of HCN, and the electron impact energy loss spectra of HCN and DCN. The present investigation supports an earlier assignment of the orbital sequence in HCN. New vibrational data are presented and the Rydberg series and valence transitions are reinvestigated. The adiabatic ionization energies for the 1π and 5σ orbitals in HCN are found to be 13.607 ± 0.002 eV and 14.011 ± 0.003 eV respectively.As mentioned above the investigation of the Rydberg series indicated that the first IP at 13.607 eV is the 1π ionization and the second IP at 14.011 eV is the 5σ ionization. A comparison of the experimental and theoretical intensity ratio between the two first PES progressions also supports this assignment. It is further supported by the fact that in the second IP the ν₃ vibration frequency is not changed as much as it is in the first IP, which is in agreement with the PES of N₂ and CO. The analysis of the bending vibrations also supports this ordering of the orbitals.The same orbital assignment has recently been proposed by Frost et al.⁵, using a comparison with the HCP photoelectron spectrum. The present paper supports their assignment of orbitals and (00⁰0)-(00⁰0) transitions. There are, however, some disagreements concerning the vibrational analysis. This is probably due to the fact that the HCN spectrum of Frost et al.⁵ revealed less structure than ours. As indicated by Figure 5 there is possibly still more structure to be revealed.     

Detection and quantification of multiple molecular species in mainstream cigarette smoke by continuous-wave terahertz spectroscopy

Continuous-wave terahertz spectroscopy by photomixing is applied to the analysis of mainstream cigarette smoke. Using the wide tunability of the source, spectral signatures of hydrogen cyanide (HCN), carbon monoxide (CO), formaldehyde (H2CO), and water (H2O) have been observed from 500 to 2400 GHz. The fine spectral purity allows direct concentration measurement from the pure rotational transitions of HCN and CO. The quantification of the measurement was validated by the means of a calibration gas containing CO. The potential of this technique for trace gas detection is demonstrated with an estimated detection limit of HCN equal to 9 parts in 10(6).     

Ionization potentials of HCN and HNC by a Green's function method

The vertical valence ionization potentials of HCN and HNC have been calculated by a many-body Green's function method using extended basis sets including polarization functions. For HCN the agreement of the computed ionization potentials with experiment is very satisfactory. The ordering is 1π, 3σ, 2σ. The ionization potentials of HNC have not been measured yet. The calculated ordering is 3σ, 1π, 2σ. The electronic structure of the two molecules is seen to differ.     

Spin–spin coupling constants in linear substituted HCN clusters

The indirect nuclear spin–spin coupling constants of homogeneous hydrogen-bonded HCN clusters are compared with those of inhomogeneous HCN clusters where one of the terminal HCN molecules is substituted by its isomer HNC and by LiCN. Both the intra- and intermolecular (across the hydrogen bond) coupling constants are calculated for the linear form of the clusters containing up to three molecular monomers using different hybrid DFT functionals. The geometry of the monomers and clusters is optimised at the B3LYP/6-311++G(d,p) level. The effect of substitution by the ionic compound LiCN on the coupling constants of HCN is found to be more pronounced than that by HNC. The Ramsey parameters that form the total spin–spin coupling constants are also analysed individually. Among the four Ramsey parameters, the Fermi Contact term is found to be the dominant contributor to the total coupling constants in most cases. The presence of LiCN in the cluster tends to decrease the intramolecular Fermi Contact values, while HNC increases the same in all dimers and trimers. The contributions of localised molecular orbitals have been analysed for the HCN–HNC cluster to obtain some additional insight about the SSCC transmission mechanism along the coupling pathway.     

Microscopic insight into catalytic HCN removal over the CuO surface in chemical looping combustion

Hydrogen cyanide (HCN) is well-accepted as a main nitrogen-containing precursor from fuel nitrogen to nitrogen oxides. When using coal as fuel with a CuO-based oxygen carrier in chemical looping combustion (CLC), complex heterogeneous reactions exist among the system of HCN, O₂, NO, H₂O, and CuO particles. This work performs density functional theory (DFT) calculations to systematically probe the microscopic HCN heterogeneous reactions over the CuO particle surface. The results indicate that HCN is chemisorbed on the CuO surface, and the third dissociation step within the consecutive three-step HCN dissociations (HCN*→CN*→NCO*→N*) is the rate-determining step. Namely, the CN*/NCO* radicals can be deemed as an indicator of the performance of HCN removal due to their quite higher dissociation energies. With the existence of O₂, H₂O, and NO, the reaction mechanism of HCN conversion becomes extremely complex. Both DFT calculations and kinetic analyses determine that O₂, NO, and H₂O all significantly accelerate the consumption of CN*/NCO* radicals to produce various N-containing species (NOx or NH₃) to different extents. Finally, a skeletal reaction network in a system of O₂/NO/H₂O/HCN is concluded, which clearly elucidates that CuO exhibits excellent catalytic activity toward HCN removal.     

Chemical pumping of the far infrared HCN laser

This paper reports the observation of 337 μm and 311 μm stimulated emission from HCN in which the (11¹0)?(04⁰0) inversion has been established by photopumping of HCN and by chemical pumping with reactions between CN and H₂ or saturated hydrogen-rich organic compounds. Similarities in output pulse behavior between the discharge and chemical versions of the HCN laser are suggestive that the pumping mechanism in the discharge is the chemical reaction, CN + H₂ → HCN² + H. The well-known inefficiency of this laser is then due to the fact that the reaction is a slow one and its exothermicity does not match the energy of the upper lasing level, but depends for inversion on (randomizing) relaxation into (11¹0) among others. Substantial improvements in the power of the HCN laser cannot be made from this route.     

Harmonic Frequencies and Potential Energy Distributions of Partially Deuterated Methyl Cyanide

Although the vibrational spectra and force constants of CH₃CN and CD₃CN have been thoroughly studied, partially deuterated methyl cyanide has received much less attention. The infrared spectrum of CD₂HCN has only recently been reported1 and that of CH2DCN has not yet appeared. Normal coordinate analysis for neither partially deuterated species has appeared. We report here harmonic frequencies and potential energy distributions for both partially deuterated methyl cyanide species, CH₂DCN and CD₂HCN, based on force fields and structural parameters from CH₃CN and CD₃CN. The calculated frequencies for CD₂HCN are compared with the observed infrared frequencies. The vibrational interaction of the relatively high CN stretching frequency and the CD stretching frequencies is also discussed.     

Blue and red shifts in Rg···HCN and Rg···HNC complexes (Rg=He,Ne, Ar,Kr)

The shift in the harmonic vibrational frequency of the H–C stretch of HCN on formation of the linear Rg···HCN complexes, and of the H–N stretch of HNC on the formation of Rg···HNC complexes (Rg?=?He, Ne, Ar, Kr), has been determined by ab initio computations. These shifts are in agreement with predictions from a model based on perturbation theory and involving the first and second derivatives of the interaction energy with respect to displacement of the H–C (H–N) bond length from its equilibrium value in the monomer. Small blue shifts were obtained for He···HCN, Ne···HCN and He···HNC, while red shifts were obtained for the other weakly bound complexes. These vibrational characteristics are rationalized by considering the balance between the interaction energy derivatives obtained from the perturbative model. For all complexes, the IR intensity of the H–C or H–N stretch was increased from the isolated monomer values on complexation.     

Adsorption of HCN molecules on Ni,Pd and Pt-doped (7, 0) boron nitride nanotube: a DFT study

We studied affinity of pure and Ni, Pd and Pt-doped (7, 0) boron nitride nanotubes (BNNTs) to toxic HCN molecules using density functional theory calculations. The results indicated that the pure (7, 0) BNNTs can weakly adsorb HCN molecules with adsorption energy of ?0.2474 eV. Upon adsorption of HCN molecules on this nanotube, the band gap energy was decreased from 3.320 to 2.960 eV. The more negative adsorption energy between these transition metal-doped (7, 0) BNNTs and HCN molecules indicated that doping of (7, 0) BNNTs with Ni, Pd and Pt elements can significantly improve the affinity of BNNTs toward this gas. Additionally, it was found that the interaction energy between HCN molecules and Pt-doped BNNTs is more negative than those of the Ni and Pd-doped BNNTs. These observations suggested that the Pt-doped (7, 0) BNNTs are strongly sensitive to HCN molecules and therefore it may be used in gas sensor devices for detecting this toxic gas.     

Revisiting the seemingly straightforward hydrogen cyanide/hydrogen isocyanide isomerisation

Both HCN and HNC are prominent in the interstellar medium and may have significant roles in prebiotic chemistry. Considerable attention has, therefore, been accorded to the HCN ? CNH isomerisation, sometimes viewed as a prototypical unimolecular process. However, detailed analysis of the potential energy of the HCN/CNH system along its intrinsic reaction coordinate, in terms of the first and second derivatives of the energy, shows that this is not a straightforward proton transfer. It appears to involve two distinct transition regions, one in which the C–H bond breaks and the other in which the N–H forms. Between these regions is a transitory state, with all vibrational frequencies being real, in which the hydrogen is situated above the C–N bond and not directly associated with either the carbon or the nitrogen. In this state, the vibrational modes of the hydrogen are, respectively, approximately parallel and perpendicular to the C–N bond.     

CaO高温脱除氰化氢试验研究

本文在石英反应器内试验了高温脱除HCN反应机理,研究了CaO对氰化氢的脱除作用,探讨了温度、体积空速和氰化氢浓度对脱除氰化氢的影响.试验结果表明:当T<45℃,CaO促使HCN中的N元素转化到CaCN_2,当T>800℃,CaO促使HCN中的N元素全部转化为N_2;CaO在800℃时,只要体积空速小于12000 h~(-1),CaO对HCN均有接近100%的脱除效果;在体积空速10000 h~(-1)、温度800℃工况下,CaO对初始浓度范围127×10~(-6)-512×10~(-6)的HCN均有接近100%的脱除效果.     

Measurement of CO,HCN, and NO productions in atmospheric reaction induced by femtosecond laser filament

It is proved that the chemical reaction induced by femtosecond laser filament in the atmosphere produces CO, HCN, and NO, and the production CO and HCN are observed for the first time. The concentrations of the products are measured by mid-infrared tunable laser absorption spectroscopy. In the reduced pressure air, the decomposition of CO₂ is enhanced by vibration excitation induced by laser filament, resulting in the enhanced production of CO and HCN. At the same time, the CO and HCN generated from the atmosphere suffer rotation excitation induced by laser filament, enhancing their absorption spectra. It is found that NO, CO, and HCN accumulate to 134 ppm, 80 ppm, and 1.6 ppm in sealed air after sufficient reaction time. The atmospheric chemical reaction induced by laser filament opens the way to changing the air composition while maintaining environmental benefits.     

Short pulses from a plasma-controlled HCN gas laser

A pulsed plasma source inserted in the cavity of a continuous HCN gas laser has been used to control the output of the laser by varying the effective length of the cavity.     

Interaction of different types of nanocages (Al12N12, Al12P12, B12N12, Be12O12, Mg12O12, Si12C12 and C24) with HCN and ClCN: DFT,TD-DFT,QTAIM, and NBO calculations

In this work, the ability of different types of nanocages including Al₁₂N₁₂, Al₁₂P₁₂, Be₁₂O₁₂, B₁₂N₁₂, Si₁₂C₁₂, Mg₁₂O₁₂ and C₂₄ for the adsorption and detection of poisonous gases HCN and ClCN has been investigated, theoretically using the D3 dispersion corrected density functional theory (DFT-D3). The absorption spectra of HCN–nanocage and ClCN–nanocage complexes were calculated by the time-dependent density functional theory (TD-DFT) and compared with the calculated absorption spectrum of isolated nanocage to investigate the ability of nanocage for sensing of HCN and ClCN gases. It was found that the strongest interaction between HCN (ClCN) molecule and nanocage takes place when the molecule is adsorbed via its N atom on the surface of nanocage except for C₂₄. Also, it was shown that the Al₁₂N₁₂ is the best adsorbent for HCN and ClCN gases among the selected nanocages and Si₁₂C₁₂ is the best sensor for the detection of these gases using the electroconductivity and absorption spectroscopy techniques.     

Fourier transform spectra of the 2100-cm−1 bands of HCN

The 2100-cm⁻¹ bands of various isotopes of HCN have been measured with a resolution of about 0.01 cm⁻¹ using the Fourier transform spectrometer constructed by J. Brault and co-workers at the National Solar Observatory. The frequencies of 500 HCN lines obtained from absorption spectra of three different isotopic species are reported with an accuracy of approximately 0.0001 cm⁻¹. Six bands of HCN, two bands of H¹³CN, and two bands of HC¹⁵N were measured. The 001 ← 000 and 03¹0 ← 000 of H¹³CN were reported for the first time. New measurements of 03³0 ← 000 forbidden transitions (Δl = 3) were made.