Double-Rydberg anions consist of a closed-shell cationic core and two electrons in diffuse orbitals. In addition to the already characterized tetrahedral NH 4and pyramidal OH 3 -, the list of stable double-Rydberg anions includes members of the NH 3 Rand OH 2 Rsets (where R ) F, OH, NH 2 , and CH 3 ) considered here. Double-Rydberg isomers of NH 3 OH -, NH 3 NH 2 -, NH 3 CH 3 -, and OH 2 CH 3are stable minima in their potential energy surfaces and have positive, vertical electron detachment energies. Similar structures have been found for the corresponding neutrals, which all have adiabatic electron affinities that are greater than zero. Dyson orbitals pertaining to the least bound electrons of the NH 3 Rand OH 2 Ranions are distributed chiefly outside the N-H and O-H bonds of the tetrahedral nitrogen and pyramidal oxygen atoms.

Ti t l e B ro a d b a n d c h a r a c t e ri s a tio n of in-d u c t a c o u s ti c s o u r c e s u si n g a n e q uiv al e n t s o u r c e a p p r o a c h

No abstract

Reverberation enhancement is a technology which allows the reverberation time of a room to be increased. It is important to consider the effect of this technology on the other measurable attributes of the room response. The spatial variation of steady state sound pressure level and reverberation time within the room can be used to measure the extent to which the room approximates a diffuse field. A theoretical value of these quantities can be predicted for an ideal diffuse field, and the ratio between the measured and theoretical values gives a normalized measure of the diffusion of the sound field. This work investigates the changes in these measures when reverberation enhancement is applied to a room. Experimental results have shown that the normalized measures of diffusion increase with the introduction of reverberation enhancement. This implies a reduction in the homogeneity and isotropy of the sound field which may be perceived as a reduction in subjective quality.

No abstract