https://doi.org/10.1007/PL00021586
A new precise value of the absolute 23S1, F = 5/2-23P2, F = 7/2 transition frequency in 7Li+
1
Physikalisches Institut der Universität
Heidelberg, Philosophenweg 12, 69120 Heidelberg, Germany
2
Gesellschaft für Schwerionenforschung (GSI),
Planckstraße 1, 64291 Darmstadt, Germany
Corresponding author: a r.neumann@gsi.de
Received:
3
November
1997
Revised:
10
March
1998
Accepted:
27
May
1998
Published online: 13 August 2013
The absolute frequency 
of the optical electric-dipole
transition between the metastable 1s2s
3S_1,
F=5/2
and the short-lived 1s2p
3P_2, F=7/2
hyperfine structure sublevels of
the helium-like 
ion in its rest
frame was determined by combining
Doppler-free saturation spectroscopy and laser heterodyning. One of two
cw single-mode dye lasers was locked to the calibrated w-component
of the [R(85) 26-0]-line in the
(B-X)-system of the
-molecule at 
MHz.
While crossing two counterpropagating beams
of the other laser perpendicularly
(lab angle 
)
with a low-velocity ion beam and tuning its frequency over
the 
transition under study,
the distance of the Lamb-dip center frequency
from 
was obtained by
mixing both laser frequencies
with an avalanche diode and registering
their beat frequency at about 4 GHz with a
quartz-stabilized high-frequency counter.
The Lamb-dip position was measured for different
ion velocities β
(in units of the velocity of light)
in the range of
. The parameters
and 
of the relativistic
Doppler formula 
were extracted via
a fit to the experimental data set
,
providing 
MHz
and 
.
This result of differs noticeably from
MHz,
measured by another group in a
collinear-beam configuration at an ion beam
propagating with 
.
PACS: 32.30.Jc – Visible and ultraviolet spectra / 06.30.Ft – Time and frequency / 07.57.Yb – Other infrared, submillimeter wave, microwave, and radiowave instruments, equipment, and techniques
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1998
