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991.
992.
Mathematical techniques are presented which have proved useful in assigning the laser magnetic resonance pure-rotation spectrum of HO2, i.e., useful in assigning an absorption spectrum obtained when molecular energy levels are Zeeman shifted by an external magnetic field until transition frequencies coincide with a fixed-frequency radiation source. The techniques described should have general applicability to the laser magnetic resonance vibration-rotation spectrum of any molecule in an orbitally nondegenerate electronic state and a doublet electronic spin state (S = 12). Equations involving both Zeeman line positions and Zeeman line intensities are presented. These allow the assignment of MJ quantum numbers, the determination of the spin-rotation interaction constant γ and rotational quantum number N for both the upper and the lower state, and the determination of the zero-field transition frequency. The equations can be used without prior knowledge of the molecular structure or energy levels.  相似文献   
993.
Results derived previously for the rotational levels of the eight-framework and three-large-amplitude vibrational problem in N2H4, using a tunneling formalism based on a treatment of the vibration-rotation problem as a whole, are rederived here in a much simpler fashion, using a tunneling formalism based on separate treatment of the vibrational and rotational problems. The present formalism is thus much more akin to the usual vibration-rotation formalism, and the origins of the various contributions to the vibration-rotation energy levels can be understood relatively easily. It is convenient here, as earlier, to make extensive use of permutation-inversion and extended-group (double-group) ideas, but it is necessary in the present treatment to consider tunneling between 16 minima in molecular coordinate space, i.e., between a number of minima which is twice the number of nonsuperimposable molecular frameworks that can actually be constructed for N2H4.  相似文献   
994.
Lee MW  Paul J  Sivaprakasam S  Shore KA 《Optics letters》2003,28(22):2168-2170
An experimental study of a chaotic optical communication scheme using an external cavity laser diode to encode a message is reported. The message is decoded in closed- and open-loop receiver schemes. Both schemes show effective decoding of a 1-GHz message. The synchronization and effectiveness of encoding are compared in both schemes.  相似文献   
995.
996.
The gas phase reactions between NH3 and the protonated amines MeNH3+, EtNH3+, PriNH3+, and Bu(t)nH3+ have been studied by high level ab initio methods. Mass spectrometric experiments yielded no significant reaction products; this result being consistent with the calculated reaction barriers. The potential energy profiles for both nucleophilic substitution (SN2) and elimination (E2) pathways have been investigated. Both back side Walden inversion (SNB) and front side (SNF) nucleophilic reaction profiles have been generated. The SNB reaction barriers are found to be higher for the more alkyl substituted reaction centres. Reaction barrier trends have been analysed and compared with the results of a similar study of the H2O-ROH2+ system (R = Me, Et, Pri, and Bu(t)).  相似文献   
997.
998.
999.
[structure: see text] Long-chain fatty acid enol ester 1 is the major metabolite of a new family of small molecules isolated from the heterologous expression of environmentally derived DNA. A versatile synthesis of 1, in which an aromatic acetaldehyde is O-acylated with a long-chain acyl chloride allowed for the rapid construction of both the isolated product (1) and a number of structural analogues (including 8, 17, and 18).  相似文献   
1000.
An efficient synthesis of 2,4-methanoproline from serine is described. The cyclobutane is formed by a sensitized intramolecular [2+2] photoaddition.  相似文献   
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