arXiv subjects

Guangcan Yang

Publications and source records attributed to Guangcan Yang.

4 recordsLinked to original sources

arXiv2009

Modulation of Field Emission Resonance on photodetachment of negative ions on surface

The interaction between the field emission resonance states and the photodetached electron in an electric field is studied by semiclassical theory. An analytical expression of the photodetachment cross section is derived in the framework. It is found that the Stark shifted image state modulates the photodetachment cross section by adding irregular staircase or smooth oscillation in the spectrum. When the photodetached electron is trapped in Stark shifted image potential well, the detachment spectrum displays an irregular staircase structure which corresponds to the modified Rydberg series. While the photodetached electron is not bound by the surface potential well, the cross secton contains only a smooth oscillation due to the reflection of electronic wave by the field or the surface.

physics.atom-ph↗

arXiv2006

Photodetachment of H- in a quantum well

The photodetachement of H- in a quantum well is investigated based on closed orbit theory. It is found the distances between the ion and the two hard walls modulate the cross section of photodetachment. For the hard walls perpendicular the polarization of photons, the detachment spectrum displays a staircase structure. The pattern of staircase is modulated by the ratio of distances from the ion to the two walls while the distance controls step interval of the staircase structure.

physics.atom-ph↗

arXiv2005

Coincidence Problem in an Oscillating Universe

We analyze an oscillating universe model in brane world scenario. The oscillating universe cycles through a series of expansions and contractions and its energy density is dominated by dust matter at early-time expansion phase and by phantom dark energy at late-time expansion phase. We find that the period of the oscillating universe is not sensitive to the tension of the brane, but sensitive to the equation-of-state parameter $w$ of the phantom dark energy, and the ratio of the period to the current Hubble age approximately varies from 3 to 9 when the parameter $w$ changes from -1.4 to -1.1. The fraction of time that the oscillating universe spends in the coincidence state is also comparable to the period of the oscillating universe. This result indicates that the coincidence problem can be significantly ameliorated in the oscillating universe without singularity.

astro-ph↗

arXiv1998

Semiclassical Green Function in Mixed Spaces

A explicit formula on semiclassical Green functions in mixed position and momentum spaces is given, which is based on Maslov's multi-dimensional semiclassical theory. The general formula includes both coordinate and momentum representations of Green functions as two special cases of the form.

quant-ph↗