We present a novel technique to frequency lock a laser to an optical cavity. This technique, tilt locking, utilizes a misalignment of the laser with respect to the cavity to produce a nonresonant spatial mode. By observing the interference between the carrier and the spatial mode one can obtain a quantum-noise-limited frequency discriminator. Tilt locking offers a number of potential benefits over existing locking schemes, including low cost, high sensitivity, and simple implementation. 相似文献
Tetrakis(dimethylamino)ethene (TDAE) and trimethylamine react with anhydrous unsaturated fluorocarbons to produce, ‘in situ’, powerful fluoride- ion sources. These are used to initiate carbon- carbon bond forming reactions eg. oligomerisation and polyfluoroalkylation, and many of these reactions occur efficiently in the absence of a solvent. 相似文献
The α,β-unsaturated ketone yields with allene the photocycloadduct predicted by our empirical photoaddition rule and the byproduct 7. The formation of this material may be rationalized by the sequence → → → → . The isomeric ketone is unreactive under the same conditions, since α addition is prohibited by the rule and β addition is severely blocked. 相似文献
A flow system has been developed to study relative rate coefficients of hydroxyl radicals reacting with alkanes under conditions relating to tropospheric chemistry. Relative Arrhenius parameters have been measured over the temperature range 243–328 K for pairs of alkanes from a list consisting of n-butane, 2-methylpropane, n-pentane, n-hexane, 2,2- and 2,3-dimethylbutane, 2,3,3-trimethylbutane, and 2,3,4-trimethylpentane. The results have been incorporated into a Structure-Activity Relation for hydroxylalkane reactions which leads to the following group rate coefficients for a temperature range of 240–500 K. 相似文献
We propose a model to explain the exponential dependence of the electron transmission coefficient through ultra-thin (4–12 Å average thickness) evaporated films of Al2O3. The mechanism involves molecular pinholes in the Al2O3 rather than tunneling. 相似文献
By photolyzing azomethane over the temperature range 331–491 K in the presence of trifluoroacetone the kinetics of the addition reaction (1), ?H3 + CF3COCH3 → CF3C(?)(CH3)2 have been studied. Detailed analyses have shown that the principal product of the adduct radical, CF3C(?)(CH3)2, is CH3COCH3 from reaction (?2), CF3C(?)(CH3)2 → CH3COCH3 + ?F3. The rate constant of the addition reaction has been determined to be k1(dm3/mol s) = (4.5 ± 1.4) × 107 exp(-(3370 ± 120)/T) over the temperature range 331–491 K, based on the value k3 = 2.2 × 1010 dm3/mol s for the reaction (3), 2?H3 → C2H6. The results are discussed in relation to existing data for radical additions to groups. 相似文献