Observation of Noise‐Triggered Chaotic Emissions in an NMR‐Maser

We report a new phenomenon observed when the magnetization of dissolved hyperpolarized ¹²⁹Xe is intense and opposite to the Boltzmann magnetization. Without radio‐frequency (rf) excitation, the system spontaneously emits a series of rf bursts characterized by very narrow bandwidths (0.03 Hz at 138 MHz). This chaotic NMR‐maser illustrates the increase in the complexity of spin dynamics at high magnetization levels by unveiling an inhomogeneous spatial organization of the xenon magnetization and an apparent dependence of the xenon transverse relaxation time on its polarization and/or on time.     

Sum rules involving coefficients of fractional parentage

Some sum rules involving the coefficients of fractional parentage are obtained. It is shown how these may be used to obtain expressions for the number of independent states in the (jⁿ)^J,T configuration.     

Sur la composition de l'arôme de cacao

A gas-chromatographic separation of cocoa aroma, followed by infra-red and mass-spectrometric identification, has yielded, besides 22 of the 91 previously described constituents, 35 new substances (8 aliphatic, 1 alicyclic, 7 aromatic, 9 o-heterocyclic, 4 pyrrolic, and 6 pyrazinic).     

Directing effect of a neighboring hydroxyl substituent on base-catalyzed enolization of a ketone

Evidence is presented that a neighboring hydroxyl substituent may exert a directing effect on the base-catalyzed enolization of a cyclohexanone derivative.