A model study of the laser-induced stabilization of a collision complex

The possibility of stabilizing a collision complex by stimulated emmission with coherent radiation is explored for a model. three-atom system. The lifetimes of several resonance states of this system were obtained previously and are used in a simple two-level model to describe the interaction of radiation with a resonance state and a true bound state. For the case where the energy difference between the two levels is time independent, simple, analytical expressions are used to obtain the time-dependent transition probability. Numerical solutions are obtained for the more realistic case where this energy difference is time dependent. For both cases, a substantial transition probability for stabilization is calculated for moderate laser intensities (e.g. 8.1 kW/cm² for an assumed dipole matrix element of 0.01 D).     

Electron excitation in atoms and molecules by neutron-nucleus scattering

The quantum theory of electron stimulated desorption developed in two preceding papers is presented in a WKB like form and is applied to the desorption of hydrogen and oxygen from tungsten. Retunnelling processes are taken into account and manifest themselves in an imaginary part in the potential of the desorbing particles. This imaginary part together with a non zero width of the wavepacket leads to quantum effects in the motion of the desorbing particles modifying the corresponding classical results of the reduction factor and of the energy conservation. The modifications turn out to be quite large for hydrogen as well as for oxygen increasing the reduction factor by several orders of magnitude. The isotope effect also is changed appreciable. The parameters of the model are determined from corresponding experimental data such as vibrational levels of the adsorbates, the energy distribution of the desorbing particles and the reduction factor.     

A novel SRN1 substitution: the reaction between the anion of 2-nitropropane and 3-bromo-1-nitrocyclohex-1-ene

X-Ray crystallography has been used to determine the unusual cyclopropyl structure for the product of the S_RNl reaction between the anion of 2-nitropropane and 3-bromo-1-nitrocyclohex-1-ene.     

Radical-nucleophilic substitution (SRN1) reactions: preparation and reactions of aliphatic α-Nitro-azides

α-Nitro-azides were prepared by two routes involving intermediate radical-anions, and undergo substitution by an S_RN1 mechanism with azides, sulphinates, and thiolates to give loss of nitrite, and with nitronates to give loss of azide.     

Bounds for the expectation of the kth root of a random variable

Exact bounds for the mean value of a fractional moment, such as the sample standard deviation, are considered. These bounds are compared with those found by summation techniques applied to computer extended series. An expansion involving an arbitrary parameter is introduced, and now best bounds are found by optimization. There are applications to bounds for a certain class of quadrature problem.     

Prediction and assignment of the FIR spectrum of hydrogen peroxide

Millimeter and submillimeter microwave studies are used to predict and assign the FIR rotational-torsional spectrum of hydrogen peroxide. Special attention is given to the strong Q-branch features that have recently been used by Traub and Chance to place an upper limit on the atmospheric abundance of hydrogen peroxide. In addition, 67 new transitions are reported in the 400–1000 GHz region.     

s- and p-wave neutron spectroscopy: Part VII. Widths of Neutron Resonances

Neutron reduced widths Γ_n⁰ and Γ_n¹ are reported for about 200 resonances observed in neutron total cross sections of Ca^{40, 44}, Ti⁴⁸, Cr^{50, 52, 54}, Fe^{54, 56}, Ni^{58, 60}, Sr⁸⁸, Y⁸⁹, Sn¹²⁴, Te¹³⁰, Ba^{136, 138}, and Pb^{206, 207, 208}, in the energy region 1 to 200 ^kev. Average parameters $\text{Γ}{}_{\mathrm{n}}{}^0$, $\text{Γ}{}_{\mathrm{n}}{}^0\text{D}$, and $\text{Γ}{}_{\mathrm{n}}{}^{\mathrm{(1)}}\text{D}$ have been derived and the Wigner distribution for local spacings and the Porter-Thomas distribution for reduced widths are verified for the resonances in the even-even nuclei Ca⁴⁰, Fe⁵⁶, Ni⁵⁸, and Ni⁶⁰. A simple method of area analysis which is less tedious and time consuming than the method reported before in Part III is also described.