Based on primary range [Formula: see text], relationships among parameters of secondary electron yield [Formula: see text] and the processes and characteristics of secondary electron emission (SEE) from negative electron affinity (NEA) semiconductors, the universal formulas for [Formula: see text] at [Formula: see text] and at [Formula: see text] for NEA semiconductors were deduced, respectively; where [Formula: see text] is incident energy of primary electron. According to the characteristics of SEE from NEA semiconductors with [Formula: see text], [Formula: see text], deduced universal formulas for [Formula: see text] at [Formula: see text] and at [Formula: see text] for NEA semiconductors and experimental data, special formulas for [Formula: see text] at 0.5[Formula: see text] of several NEA semiconductors with [Formula: see text] were deduced and proved to be true experimentally, respectively; where [Formula: see text] is the [Formula: see text] at which [Formula: see text] reaches maximum secondary electron yield. It can be concluded that the formula for [Formula: see text] of NEA semiconductors with [Formula: see text] was deduced and could be used to calculate [Formula: see text], and that the method of calculating the 1/[Formula: see text] of NEA semiconductors with [Formula: see text] is plausible; where [Formula: see text] is the probability that an internal secondary electron escapes into vacuum upon reaching the surface of emitter, and 1/[Formula: see text] is mean escape depth of secondary electron.

Based on the experimental maximum escape depth [Formula: see text], [Formula: see text] of rediffused electrons from atomic number [Formula: see text] metal at incident energy of primary electron [Formula: see text], the relationship among [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] in the energy range of 9.3[Formula: see text]keV[Formula: see text]40[Formula: see text]keV was obtained and proved to be true by experimental data. According to the experimental results of rediffused electrons, the characteristics of secondary electron emission, relationships among parameters of rediffused electrons and the main processes of rediffused electrons emission, the formula for [Formula: see text] backscattering coefficient [Formula: see text], [Formula: see text], [Formula: see text] of [Formula: see text] metal films with film thickness [Formula: see text] as a function of [Formula: see text], Z and was deduced, and the results were analyzed. It is concluded that the deduced formula for [Formula: see text], [Formula: see text], [Formula: see text] can be used to calculate [Formula: see text], [Formula: see text], [Formula: see text] in the energy range of 9.3[Formula: see text]keV[Formula: see text]40[Formula: see text]keV. The secondary electron yield [Formula: see text] from thin films are applied in more and more fields such as electronic information technology, accelerator and space flight, and [Formula: see text], Z, [Formula: see text] is an important parameter of [Formula: see text] from [Formula: see text] metal films. So deducing the formula for [Formula: see text], [Formula: see text], [Formula: see text] in this study is necessary.

Novel feature of high order harmonic generation process for molecules is presented for several molecules at their equilibrium geometries. The high order harmonic spectra reveal additional sidebands for each odd harmonic, which are a consequence of the resonant coupling of two valence orbitals, a mechanism analogous to Mollow triplets known from quantum optics. Strong modification of the high order harmonic generation process is illustrated with time frequency analysis in which there appear additional minima dependent on the Rabi frequency for the corresponding transition. The orbital coupling further leads to the modification of the electron dynamics which is presented using total electron density difference maps.

We have studied the polarization and ellipticity of high-order harmonics from nitrogen molecules using the time-dependent density functional theory. The results of our numerical calculations are in excellent agreement with the data of recent experiments. The theoretical analysis of our results reveals that at least three contributions, namely those from the HOMO, the HOMO-1, and the HOMO-2 orbitals, contribute to the observed high harmonic spectra. Furthermore, we confirm that a proper account of the distribution of the alignment in the molecular ensemble is necessary to obtain agreement with the experimental data.