Quantum yields, double photoionization

Figure 3 The photoionization quantum yields (rji) of CH4 as a function of the incident photon energy measured via the double ionization chamber and synchrotron radiation as mentioned in Section 2.1. The bandpass was 0.1 nm, which corresponds to the energy width of 32 meV at the incident photon energy of 20 eV. The vertical ionization potentials of the ionic states involved are indicated by the vertical bars [11] along with the first adiabatic ionization potential by the arrow [17]. (From Ref. [7]. Reprinted with permission from Elsevier Science.)...

In Fig. 7 [7], we compared the photoionization quantum yields (t/,) of CH4, C2H6, and C3H8, which were measured by our group using the double ionization chamber and synchrotron radiation, as described in Section 2.1. The photon energies are considered in two ranges, as follows, in terms of the behavior of the t/, curves as a function of the incident photon energy [7] ... 

Gorner H (1994) Photochemistry of DNA and related biomolecules quantum yields and consequences of photoionization. J Photochem Photobiol B Biol 26 117-139 Gorner H, Wala M, Schulte-Frohlinde D (1992) Strand breakage in poly(C), poly(A), single- and double-stranded DNA induced by nanosecond laser excitation at 193 nm. Photochem Photobiol 55 173-184... 

Figure 15. Quantum yields of double photoionization, as defined in the text, for a selection of molecules and for atomic Xe, with the wavelengths used.

Quantum yields in double photoionization involving deep inner shells of molecules have not yet been determined, but are expected to show the same general pattern of behavior. 

For some molecules the quantum yield of double photoionization is low and the electron energy distributions are both flat and relatively smooth. This... 

Figure 18. Final states and quantum yield in double photoionization of HBr. The step structure of the yield is a further indication that most superexcited states of HBr+ dissociate rather than autoionize to the doubly charged cation.

Figure 21. The inner valence Auger effect in formaldehyde (methanal). The broad peak in the regular photoelectron spectrum near 34 eV is an inner valence (IV) band based on C2s ] ionization. It recurs as a peak in the electron distribution for double photoionization and in the quantum yield. The uppermost curve shows the spectrum of HCH02+, where the ground state is strongly populated by this effect. 

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