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<div><font face="Times New Roman" color="#000000"><b>Seminar on<br>
<br>
Modern Optics and Spectroscopy<br>
<br>
<br>
<i>Toward pure electronic spectroscopy<br>
<br>
</i>Vladimir Petrovic</b>, MIT<br>
<br>
Tuesday, November 25, 2008<br>
<br>
<br>
12:00 - 1:00 p.m.<br>
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<br>
<br>
When the electronic transition dipole moment among molecular Rydberg
states is significantly larger than the permanent dipole moment of the
ion core, interactions with an external electric field that change the
quantum numbers for the Rydberg electron, but conserve the quantum
numbers of the ion core, are dominant. Such same-n* Rydberg-Rydberg
interactions can be observed in both the Stark effect and in
transitions. We have characterized the Stark effect in Rydberg states
of CaF, which has a Rydberg system of paradigmatic character with one
of the largest dipole moments in a molecular ion, and which is among
the molecules with the largest body of data available. The highly
polar ion-core causes strong<i> l</i>-mixing, which distorts the
expected patterns. Use of polarization diagnostics to assign the
rotational quantum number,<i> N</i>, and the Stark effect to access
and assign the<i> N+</i> quantum number for higher-<i>l</i> states,
provided information about the penetrative character of nominally
core-nonpenetrating states, thus bridging our longrange and MQDT
models. We are developing time domain THz and chirped-pulse microwave
spectroscopic techniques for studying pure electronic spectra in
transmission, which yield same information as in the Stark effect but
without difficult detective work. In addition, models that
relate the observed transition intensities and mixing coefficients
among different<i> l</i> series in pure electronic spectra will be
discussed.<br>
<br>
<br>
</font><font face="Times New Roman" color="#000000">Grier Room, MIT
Bldg 34-401</font></div>
<div><font face="Times New Roman" color="#000000">Refreshments served
after the lecture</font></div>
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