Helium singly excited states

In the ground state and singly excited states of helium, the electrons have a high probability of penetrating into the region near the nucleus where their... 

Comes reported structure in the ionization-efficiency curves of Ar2 and Kr2" which was dependent upon pressure and which he interpreted as being characteristic of a superposition of excitation functions of two excited states. Melton and Hamill reported two breaks above the initial onsets in the ionization-efficiency curves of Ar2 and Kr2, and they interpreted these as being due to the participation of several states in the reaction. Further evidence of the inadequacy of the single-excited-state assumption used in the steady-state kinetic treatments " was provided by the work of Becker and Lampe and DeCorpo and Lampe. These authors used a single-source mass spectrometric technique with a pulsed electron beam and a variable time-delay (reaction time) between the electron beam pulse and an ion-withdrawal pulse. It was shown that the ionization-efficiency curves depend upon the duration of the electron pulse and the time-delay (reaction time) in a manner that is consistent with the overall curve being a superposition of the excitation functions of several families of excited states. In the case of helium, comparison of the overall curves with the known excitation functions permitted some conclusions to be drawn concerning the identity of the reacting states. 

To go further, we turn to so-called all-order methods. We start by considering relativistic calculations of type carried out by Lindroth [38] and Blundell et al. [39], which account for all possible single and double excitations of the ground-state helium HF wave function. These calculations have the potential of giving an exact helium ground-state energy. 

The lifetimes of the sublevels of the excited triplet state of the Rh-trisdiimine complexes have been determined using the microwave recovery and adiabatic rapid passage techniques mentioned in Sect. 4.2. At (pumped) liquid helium temperatures it turned out that the triplet state sublevels have distinct lifetimes. As an example, we show in Fig. 8 the optically detected adiabatic transient signal as monitored for the zero-field D -1 resonance, at 2320 MHz, of the photo-excited [Rh(bpy)3] (0104)3 single crystal, at 1.4 K. The microwave frequency scan was at a rate of 2 x 10 Hz/s. Similar transients were obtained by rapid scans through the zero-field microwave transitions for the other compounds of the [Rh(phen)u(bpy)3 n] (0104)3 series. The transients fitted a biexponential function of the form... 

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