Radiative Lifetimes of Excited Electronic States in Ionic Species of Nitrogen

Abstract

The foil excitation technique, wherein a high-energy (2-MeV) beam of ions is passed through a thin (^-4000 A) carbon foil, has been used to measure lifetimes of excited electronic states in nitrogen n through V. The lifetimes were obtained by measuring the decay of optical radiation as a function of distance from the foil. The excited states were considerably above the ground state of the particular ion, and as a consequence, nonlinear population by cascading was minimal. Because of the low speed of the optical system (//8.8), only the most intense multiplets and members of multiplets were observed. The wavelength range in which transitions were observed was 2000 to 5000 A. The lifetimes measured were between 0.4 and 10 nsec. In general, these lifetimes apply to all the members of the multiplet, since the levels of origin as well as the levels of termination are closely spaced with respect to the total-angular-momentum quantum number /. Where it is possible, these lifetimes are compared with available calculations. Some transitions are untabulated and were identified through the use of a computer program.

Ground-state depletion for subdiffraction-limited spatial resolution in coherent anti-Stokes Raman scattering microscopy

“…The |1 -|2 transition between the ground state and the Raman state is set to 47 THz (1568 cm −1 , 6379 nm) and the |1 -|4 transition between the ground state and the vibrational state to 97 THz (3236 cm −1 , 3091 nm) [15]. The population lifetimes of the states |2 , |3 , and |4 are chosen to be 1 ns [18][19][20], while the coherence lifetimes are 1 ps for the electronic state |3 and 5 ps for the vibrational state |4 as well as the Raman state |2 [21,22]. Here, for generality, no nonradiative transition between states |2 and |4 is assumed, but the effect of such a transition is investigated separately (Sec.…”

Radiative Lifetimes of Excited Electronic States in Ionic-Species of Oxygen

“…P°-3p4 S (I, f-f ) transitions, however, since obvious cascading from the very strong 3d 4 P° level is observed to the 3p 4 S level at 3362.63 A already discussed. Un-fortunately there is no way of checking the lifetime of the 3p 4 S level against theoretical calculations to verify the cascading.…”

“…The disparity between the lifetimes of the cascading state and state of interest also indicates minimal, if any, cascading. This is not the case for the 3s 4 Four transitions belonging to three different multiplets were observed for O v. The upper levels involved were 3p 3 P, 3p 3 P°, and 7d 1 D a The 3p 3 p and 3p 3 P° levels have allowed transitions into them, predicted by WALTRAN, which lie primarily in the vacuum uv. None of these transitions are listed in the standard references but some may be found in a recent paper by Bockasten and Johansson.…”

Stimulated-emission pumping enabling sub-diffraction-limited spatial resolution in coherent anti-Stokes Raman scattering microscopy

“…To allow for a clear temporal separation of the effect of the control light field pair and the CARS excitation light fields, high population and coherence lifetimes are assumed for this work. Generally, the population and coherence lifetimes of CARS samples are found in a range from 10 to 1000 ps [24][25][26][27][28] and from 100 fs to 10 ps [29,30], respectively. However, this does not restrict the applicability of the presented scheme.…”