Hyperfine Studies of Hyperfine Studies of Lithium usingLithium using

Saturated Absorption Saturated Absorption SpectroscopySpectroscopy

Tory CarrTory Carr

Advisor: Dr. Alex CroninAdvisor: Dr. Alex Cronin

Hyperfine Structure of Hyperfine Structure of 66Li & Li & 77LiLi

Normal SetupNormal SetupT

rans

mis

sion

Sig

nal

-15 -10 -5 0 5 10 15frequency (GHz)

6Li D1

7Li D1+

6Li D2

7Li D2

Theoretical LimitTheoretical Limit

8

6

4

2

0

Inte

nsity

0.20.10.0-0.1-0.2Frequency (GHz)

6 MHz

ProblemProblem

Doppler Broadening “smears out” Doppler Broadening “smears out” resolutionresolution

Inte

nsity

420-2-4Frequency (GHz)

3 GHz

Normal SetupNormal SetupT

rans

mis

sion

Sig

nal

-15 -10 -5 0 5 10 15frequency (GHz)

6Li D1

7Li D1+

6Li D2

7Li D2

Theory at 375 C

Saturated Absorption SetupSaturated Absorption Setup

New SpectrumNew Spectrum30x10

-3

25

20

15

10

5

0

Tra

nsm

issi

on s

igna

l (m

W)

151050-5-10-15Frequency (GHz)

FS

HFS

HFS

7Li D2

7Li D1+

6Li D2

6Li D1

experimental data theoretical model

Saturated Absorption SignalSaturated Absorption SignalT

rans

mis

sion

Sig

nal

Frequency Scan

800MHz

Data collected at 375 C

Light as seen from the Light as seen from the atomsatoms

Pump beam

probe beamv0

Population DifferencePopulation Difference

Scan in frequencyScan in frequency

+dv

-dv

0

Theoretical ModelTheoretical Model

Isotope/ Transition Isotope/ Transition DifferenceDifference

Variation with Buffer Gas Variation with Buffer Gas PressurePressure

Temperature variationTemperature variation

Temperature variation- diff Temperature variation- diff sigsig

Maximum in difference Maximum in difference signalsignal

Maximum Signal When:

ConclusionConclusion

Limiting Factors in resolutionLimiting Factors in resolution– Other broadening mechanismsOther broadening mechanisms– Residual Doppler broadeningResidual Doppler broadening

Improvements to setupImprovements to setup– Improved alignmentImproved alignment– Reduce laser linewidthReduce laser linewidth

Further experimentsFurther experiments– Effects of polarizationEffects of polarization– Magnetic field effects Magnetic field effects