Lab

orat

ory

and

obse

rvat

iona

l stu

dies

of C

60an

d C

60+

Susa

nna

L. W

idic

us W

eave

r, M

atth

ew C

. Zw

ier,

Yun

Din

g, a

nd B

enja

min

J. M

cCal

l

Uni

vers

ity o

f Illi

nois

at U

rban

a-C

ham

paig

n

Out

line

I.M

otiv

atio

ns fo

r stu

dyin

g C

60an

d C

60+

II.

Spec

tral s

tudi

es o

f C60

III.

Obs

erva

tiona

l stu

dies

of C

60w

ith T

EXES

at I

RTF

IV.S

pect

ral s

tudi

es o

f C60

+

Mot

ivat

ions

for

Stud

ying

C60

and

C60

+

•C

60w

as d

isco

vere

d du

ring

expe

rimen

ts d

esig

ned

to si

mul

ate

outfl

ows o

f car

bon

star

s.

•C

60sh

ould

be

stab

le in

the

ISM

(~

44

eVre

quire

d to

bre

ak c

age)

.

•C

60ha

s bee

n fo

und

in se

dim

ents

re

late

d to

met

eorit

e im

pact

s.

•C

60ha

s bee

n fo

und

in L

DEF

cra

ters

.

•C

60sh

ould

be

ioni

zed

by st

ella

r rad

iatio

n an

d “C

60+

shou

ld b

e ub

iqui

tous

ly d

istri

bute

d in

spac

e.”

(Kro

toSc

ienc

e24

2, 1

988)

•3(

60)-

6 =

174

vibr

atio

nald

egre

es o

f fre

edom

•Ic

osah

edra

l(I h)

Sym

met

ry: 6

five

-fol

d ax

es, 1

0 th

ree-

fold

ax

es, 1

5 tw

o-fo

ld a

xes

•Si

xty

quan

tum

-mec

hani

cally

indi

stin

guis

habl

e (s

pin

0)

boso

ns

•Sy

mm

etry

rest

rictio

ns o

n to

tal w

avef

unct

ion

Abo

ut C

60

•4

F 1uIR

act

ive

mod

es [1

432,

118

3, 5

77, 5

28 c

m-1

]

•G

as p

hase

IR sp

ectru

m o

bser

ved

at 1

065

K; n

o ro

tatio

nal

stru

ctur

e re

solv

ed (

Frum

et a

l. Ch

em. P

hys.

Lett.

176,

199

1)

A r

otat

iona

lly c

old

spec

trum

is r

equi

red

for

com

pari

son

to

inte

rste

llar

spec

tra.

IR S

pect

rosc

opy

of C

60

Sim

ulat

ed In

ters

tella

r Spe

ctru

m a

t 30

Kan

d N

= 1

016

cm-2

Sim

ulat

ed L

abor

ator

y S

pect

rum

at 1

0 K

Gas

Pha

se S

pect

ral S

tudi

es o

f C60

100

W h

alog

en b

ulbs

in

a co

pper

tubi

ng c

oil

to p

rehe

at a

rgon

car

rier g

as

150

W h

alog

en b

ulbs

to

hea

t ove

n

C60

sam

ple

in o

ven

Ar

T >

600

ºC g

ives

vap

or

pres

sure

> 5

0 m

Torr

Sup

erso

nic

expa

nsio

n ad

iaba

tical

ly c

ools

C60

CW

Cav

ity R

ingd

own

Spec

tros

copy

•A

hig

h fin

esse

cav

ity is

pl

aced

aro

und

the

supe

rson

ic e

xpan

sion

.

•R

adia

tion

is c

oupl

ed in

to

the

cavi

ty, w

hich

is c

ycle

d in

and

out

of r

eson

ance

.

•W

hen

the

cavi

ty is

on

reso

nanc

e th

e ra

diat

ion

is

switc

hed

off.

•Th

e ex

pone

ntia

l dec

ay ra

te is

a d

irect

mea

sure

men

t of

abs

orpt

ion.

Cur

rent

Sta

te o

f the

C60

Exp

erim

ent

•Su

stai

ned

flow

of g

as p

hase

C60

achi

eved

•O

ptic

s for

CW

cav

ity ri

ngdo

wn

at 1

183

cm-1

curr

ently

bei

ng a

ssem

bled

•D

irect

abs

orpt

ion

N2O

spec

trum

obt

aine

d w

ith a

test

QC

L

•D

ata

obta

ined

June

200

3

•U

pper

lim

it ~

3 ×

1015

cm-2

•N

eed

labo

rato

ry sp

ectru

m!

NAS

A's

3-m

eter

IRTF

(In

fraR

edTe

lesc

ope

Faci

lity)

, Mau

na K

ea,

Haw

aii

Ast

rono

mic

al S

pect

rosc

opy

of C

60TE

XES:

Tex

as E

chel

on C

ross

Ech

elle

Spe

ctro

grap

h

Spec

tros

copy

of C

60+

The

elec

troni

c an

d in

frar

ed

spec

tra o

f C60

+w

ere

obse

rved

in n

eon

and

argo

n m

atric

es.

(Ful

ara,

Jako

bian

d M

aier

Che

m. P

hys.

Lett.

211,

199

3)

This

was

use

d as

a b

asis

for

obse

rvat

iona

l sea

rche

s and

tw

o D

IBsw

ere

attri

bute

d to

C

60+ .

(Foi

ngan

d Eh

renf

reun

dN

atur

e36

9, 1

994;

A&

A31

9, 1

997)

C60

+

Ne

mat

rix

HD

183

143

Is C

60+

Rea

lly a

DIB

Car

rier

? C

riter

ia fo

r the

se tw

o D

IBst

o be

C60

+ :

1.Th

e sa

me

FWH

M

2.M

atch

ing

rela

tive

inte

nsiti

es to

lab

spec

tra

3.G

as-m

atrix

shift

s con

sist

ent w

ith e

xper

imen

tal i

nfor

mat

ion

A g

as p

hase

C60

+sp

ectr

um is

req

uire

d to

an

swer

this

que

stio

n de

finiti

vely

.

“The

cas

e fo

r C60

+is

bet

ter t

han

for m

any

othe

r [D

IB] c

andi

date

s and

now

rest

s in

the

cour

t of

labo

rato

ry sp

ectro

scop

ists

.” (Je

nnis

kens

et a

l. A&

A32

7, 1

997.

)

Gas

Pha

se S

pect

ral S

tudi

es o

f C60

+

100

W h

alog

en b

ulbs

in

a co

pper

tubi

ng c

oil

to p

rehe

at a

rgon

car

rier g

as

150

W h

alog

en b

ulbs

to

hea

t ove

n

C60

sam

ple

in o

ven

Ar

T >

600

ºC g

ives

vap

or

pres

sure

> 5

0 m

Torr

Sup

erso

nic

expa

nsio

n ad

iaba

tical

ly c

ools

C60

Ele

ctro

de a

t -V

giv

es a

di

scha

rge

for C

60+

expe

rimen

t

Al 2O

3 sp

acer

& e

poxy

to

sea

l and

insu

late

Cur

rent

Sta

te o

f the

C60

+E

xper

imen

t•

CW

cav

ity ri

ngdo

wn

achi

eved

at

950

nm

•D

isch

arge

sour

ce b

uilt

from

hig

h te

mpe

ratu

re

mat

eria

ls a

nd te

sted

w

ith N

2/Ara

nd C

60/A

r

•C

old

N2+

spec

trum

ob

serv

ed w

ith N

2/Ar

disc

harg

e w

hile

hea

ting

gas a

nd o

ven

to >

600

ºC

•Th

e se

arch

for t

he C

60+

spec

trum

is u

nder

way

Col

d N

2+Io

ns a

t Hig

h R

esol

utio

n an

d Se

nsiti

vity

Ack

now

ledg

emen

ts

•Th

e M

cCal

l Gro

upEs

peci

ally

Bria

n Po

hrte

, B

rian

Bru

mfie

ld,

and

Jeff

Car

ter

•Pr

ince

ton

(QC

L):

Cla

ire G

mac

hl

Scot

t She

ridan

•U

C D

avis

(TEX

ES):

Dan

a N

ucci

telli

Mat

thew

Ric

hter

•N

ASA

Lab

orat

ory

Ast

roph

ysic

s Pro

gram

•N

SF

•A

CS

PRF

•D

reyf

us F

ound

atio

n