Related Experiment Video
Updated: Jul 13, 2026

Measurement and Analysis of Atomic Hydrogen and Diatomic Molecular AlO, C2, CN, and TiO Spectra Following Laser-induced Optical Breakdown
Published on: February 14, 2014
Experimental determination of the lifetime for the 2p3d(1P0) helium doubly excited state
J G Lambourne1, F Penent, P Lablanquie
1DIAM, Université P & M Curie, 75252 Paris 5, France.
Abstract:
Two recent theoretical studies [C. Liu, Phys. Rev. A 64, 010501 (2001)]; M. Zitnik, ibid. 65, 032520 (2002)]] predict that the fluorescence lifetimes of helium doubly excited states converging to He+ N=2 should be longer than that of the He+ 2p ion state. This effect is caused by the electric field of the outer electron which, through Stark mixing, gives the inner fluorescing electron some series specific, stabilizing 2s character. We have obtained the first experimental evidence that confirms this effect by measuring the lifetime of the 2p3d(1P0) doubly excited state. This was determined to be 190+/-30 ps compared to 100 ps for the He+ 2p ion state. The measurements were performed using short pulses of synchrotron radiation to form doubly excited states and recording the arrival time of photons from fluorescence.
Related Concept Videos
The Bohr Model
Emission Spectra
The Pauli Exclusion Principle
The Aufbau Principle and Hund's Rule
Molecular Orbital Theory II
¹H NMR of Labile Protons: Deuterium (²H) Substitution

