M. Vogel

for the SPECTRAP collaboration

PRECISION SPECTROSCOPY ON HIGHLY CHARGED IONS

DOUBLE-RESONANCE SPECTROSCOPY IN HCI

Manuel Vogel

HCI level schemeHCI level scheme

F=5m =-4F

HFS

MW2F=4 m =-3F

m =-4F

m =-5F

......

MW1

h =g B MW F 0

typically 10 -10 Hz14 15

typically 10 -10 Hz9 10

H-like ion in external B-field: hyperfine levels are split into Zeeman sublevels

example: 209Bi82+ I=9/2

F=I+J, F=I-J J=1/2 (ground state)

Manuel Vogel

relationsrelations

nuclear g-factor gI

electronic g-factor gJ

atomic (ionic) g-factor gF

using this relation: measure any 2 numbers independently and get the third one free

e.g.

gI from NMR (but: diamagnetic shielding)gJ from Stern-Gerlach-Experiments

gF from double-resonance experiments

Manuel Vogel

known valuesknown values

+ a large number of gI from NMR

gJ

HFS

Manuel Vogel

double-resonance techniquedouble-resonance technique

idea: perform a laser-microwave double-resonance experimentand use the light from the optical transition as a probe for the Zeeman transitions

gF

gF‘

Manuel Vogel

case 1: only one gcase 1: only one gFF measured measured

we can use

to get either

or

I,F

I,F

small,well-known from theory

Manuel Vogel

case 2: two gcase 2: two gFF measured measured

if gF is measured for two different F, then we can simulaneously and independently get

and

(this only works for I>1/2)

Manuel Vogel

this meansthis means

...we can obtain electronic and nuclear magnetic moments (g-factors) simultaneously

with a relative accuracy of 10-7 or better (depending on the system)

...we are independent from diamagnetic shielding,i.e. shielding effects can for the first time be measured

and theory can be tested

BLIND SPECTROSCOPY

Manuel Vogel

optical spectroscopy by MW measurementoptical spectroscopy by MW measurement

idea: perform laser cooling on forbidden transition andprobe the effect by the corresponding motional frequency shift

in a magnetic bottle.

forbidden transition can be identified with a precision of better than 10-10

using only a single ionno optical detection

Manuel Vogel

axial laser cooling – magnetic bottleaxial laser cooling – magnetic bottle

z

initial resistive cooling,pick up,

rf frequencymeasurement

Manuel Vogel

frequency shiftfrequency shift

i.e. 10-6 to 10-5 shift

10-10 sensitivity

0 50 100 150 200 250 300 350 400 450 5001E-9

1E-8

1E-7

1E-6

1E-5

1E-4

1E-3

B2=4mT/mm2

B2=40mT/mm2

RE

LA

TIV

E A

XIA

L F

RE

QU

EN

CY

SH

IFT

TRAPPING VOLTAGE [V]

B2=400mT/mm2

Manuel Vogel

sideband spectrumsideband spectrum

OPT OPT z+ OPT z+2 OPT z+3 OPT z- OPT z-2 OPT z-3

I[arb. units]

0.15

0.30

0.45

0.60

0.75

0.90

1.0

0.5

1.5

T[K]

2.5

6.5

15

"carrier"

red sidebandsblue sidebands

OPT OPT z+10 OPT z+20 OPT z+30 OPT z-10 OPT z-20 OPT z-30

I[arb. units]

0.02

0.04

0.06

0.08

0.10

0.12

10

0.5

15

T[K]

2.5

6.5

15

"carrier"

red sidebands

blue sidebands

Pb1+

Pb81+

Manuel Vogel

cooling ratescooling rates

Manuel Vogel

pro: estimated accuracy better than 10-10

needs only a single ionno optical detection system necessary

acceptable laser cooling times due to high detection sensitivity

can use existing/planned g-factor setup (replace MW by cooling laser)

Thank you for your attention

conclusionconclusion