I wanted to know when can excitation of electron take place i.e excitation of electron only takes place between subshells having same principal quantum number or is it seen by difference in energy level?
For example look at configuration of Pt- [Xe] 6s2 4f14 5d8. It has vacant 5f, 6d, 6p. I know Pt is a noble metal and generally excitation may not take place, but for a moment let us forget it and assume excitation can take place. Can electrons of 6s excite to 5f? Or only 6d and 6p. Can electrons of 4f excite to 6d or 6p?

  • $\begingroup$ All these excitations are possible. Some may need more energy than others to take place. And some are not really probable, because they may violate selection rules. Do you know the selection rules ? $\endgroup$
    – Maurice
    Aug 24, 2021 at 11:02
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    $\begingroup$ The selection rules govern how an electron is observed to transition (excite upwards or relax downwards) from one orbital to another. Formally, they are written as: ΔS=0 ΔL=0,±1 L+S=J ∴ΔJ=0,±1 where ΔS is the change in intrinsic angular momentum of the electron (spin multiplicity is 2S+1), ΔL is the change in orbital angular momentum, and ΔJ is the change in the total angular momentum. $\endgroup$ Aug 24, 2021 at 11:30
  • $\begingroup$ are you talking about these ? $\endgroup$ Aug 24, 2021 at 11:30
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    $\begingroup$ A transition is allowed if it respects the selection rules that you have mentioned. If they don't, the transition is forbidden. it does not mean that they do't take place. It only means that their probability is small, or that the absorption coefficient is much lower than for allowed transitions. $\endgroup$
    – Maurice
    Aug 24, 2021 at 16:30
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    $\begingroup$ "I know Pt is a noble metal and generally excitation may not take place," - if you're shining light / EM radiation on the atom, then excitation of an electron is perfectly possible as long as photons of the correct wavelength are supplied (and as long as the selection rules are obeyed). It doesn't matter how noble the element is. "Noble" is merely a crude description of their chemical properties; it has no bearing on the underlying, more fundamental, physics. $\endgroup$
    – orthocresol
    Sep 4, 2021 at 23:44


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