1
$\begingroup$

I need to find the deexcitation times for the transitions found in Figure 1 of Nature Phys. 8, 649 (2012), arXiv:1206.4507.

That is, what is the deexcitation time for the following transitions:

$$ ^2P_{1/2} \rightarrow {}^2S_{1/2} $$ $$ ^2P_{1/2} \rightarrow {}^2D_{3/2} $$ $$ ^2D_{3/2} \rightarrow {}^2S_{1/2} $$ $$ ^2D_{5/2} \rightarrow {}^2F_{7/2} $$

I've searched on google for pretty much everything I can think of , but I was not able to find a data table with these deexcitation times.

$\endgroup$
  • $\begingroup$ I'm voting to close this question as off-topic because it is about locating data, not physics. $\endgroup$ – ACuriousMind Oct 14 '15 at 12:14
  • $\begingroup$ @ACuriousMind How is the process of locating crucial data for a calculation not part of the process of calculating? $\endgroup$ – Emilio Pisanty Oct 14 '15 at 12:16
  • 1
    $\begingroup$ It is not about locating data, as the "data" may be very difficult to find. I do not think that pointing to a difficult to find source of information should be an issue. As specifically mentioned above, I did try and search for the "data" on my own and did not just enter a question here out of laziness. Closing a question due to purely interpretative reasons is clearly nonconstructive. $\endgroup$ – Qubix Oct 14 '15 at 12:16
  • 1
    $\begingroup$ @ACuriousMind, sir ,what you may consider part of a physics question or not, is entirely up to you. The deexcitation constants I have asked about describe the atomic system. Without these specific constants it is impossible to model the behavior of such a system. Since the constants themselves seem to be difficult to find, I asked here, in the hope that someone may actually know where to find them. As for the issue of whether or not locating essential data should be regarded as a "physics question", with all due respect, I find this worthy of ridicule. $\endgroup$ – Qubix Oct 14 '15 at 12:31
  • 1
    $\begingroup$ I don't believe that there is a consensus on "find me this data" type questions (it could fall under specific-reference), but history seems to be on the "leave open" side of things. Might be worth a Meta question. $\endgroup$ – Kyle Kanos Oct 14 '15 at 12:42
2
$\begingroup$

Most of what's making life difficult is that you're using the wrong terminology. The term "deexcitation" can be understood by a human but it is not standard or recommended, and it definitely won't be understood by a machine. What you're looking for are more normally called the state and transition lifetimes and probabilities.

The place to look is the NIST Atomic Spectra Databases, particularly the one for atomic lines. I can't link to the Ytterbium page (it's a dynamic page), but the $A_{ki}$ are the data you want - they are the transition probabilities, in $\mathrm s^{-1}$, for the transition. Invert those to get the lifetimes. If the information you want is not on there, there is a wealth of bibliographic information lying about the site which can probably help you find what you need.

For the specific transitions listed in the diagram, the NIST database only lists two, ${}^2 P_{1/2}\to{}^2 S_{1/2}$ and ${}^3 [3/2]_{3/2}\to{}^2 S_{1/2}$ (which you took down as ${}^2D_{3/2}\to{}^2 S_{1/2}$, but that is incorrect) for the Yb II spectra (note that this is the ytterbium ion, not the neutral): \begin{align} \text{Transition} & & \text{Wavelength} & & A_{ki} & & A_{ki}^{-1}\\\hline {}^2 P_{1/2}\to{}^2 S_{1/2} & & 369\:\mathrm{nm} & & 123\:\mathrm{\mu s}^{-1} & & 8.13 \:\mathrm{ns} \\ {}^3 [3/2]_{1/2}\to{}^2 S_{1/2} & & 297\:\mathrm{nm} & & 26.1\:\mathrm{\mu s}^{-1} & & 38\:\mathrm{ns} \end{align}

If you want to go beyond this you can click on the reference on the far-right corner, which then lets you find all the bibliography on the species in question. Using this you can find, for example, Phys. Rev. A 60, 2829 (1999), which gives

\begin{align} \ \ \ \ \ \ {}^2 D_{5/2}\to{}^2 F_{7/2} & &\ \ \ \ \ \ \ 3.43\:\mathrm{\mu m} & & 0.905\:\mathrm{\mu s}^{-1} & & 1.10\:\mathrm{\mu s} \end{align}

Note that this is out of the wavelength range in the NIST database.

You can get the wavelength of the final transition, ${}^2 P_{1/2}\to{}^2 D_{3/2}$, using energy level data from Atomic Energy Levels - The Rare-Earth Elements by Martin, Zalubas and Hagan, and it comes out as $2.4\:\mathrm{\mu m}$, also outside of the range in the NIST database. If you're happy with a theoretical calculation then J. Phys. B: At. Mol. Opt. Phys. 45 145002 (2012) gives estimates from $A_{ki}= 47\:\mathrm{ms}^{-1}$ to $2.98\:\mathrm{\mu s}^{-1}$, which is not very comforting, but the real issue with this transition is that it is very hard to measure.

In particular, if you put an ytterbium ion in the ${}^2P_{1/2}$ state, what it will do almost immediately is decay via the dipole transition to the ground state, ${}^2S_{1/2}$, with very little of the population ending up in the metastable ${}^2D_{3/2}$ state. What you care about, then, is the branching ratio in the decay of the ${}^2P_{1/2}$ state, which is measured at $0.0005$ by Phys. Rev. A 76, 052314 (2007), from an overall lifetime of $8.07\:\mathrm{ns}$.

| cite | improve this answer | |
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.