Transcript Neutral-ion collisions in merged beams experiments

Storage ring measurements of the
dissociative recombination of H3+: a closer look
Holger Kreckel
University of Illinois at Urbana-Champaign
TSR
Group
Oldřich Novotny*
Annemieke Petrignani
Max H. Berg
Dennis Bing
Manfred Grieser
Claude Krantz
Michael Lestinsky*
Mario B. Mendes
Christian Nordhorn
Roland Repnow
Julia Stützel
Andreas Wolf
*Columbia University, NY
University
of Illinois
Kyle N. Crabtree
Brian A. Tom
Benjamin J. McCall
Weizmann
Institute
Henrik Buhr
Stockholm
University
Richard Thomas
DR 2010, Lake Tahoe, Aug19th 2010
Holger Kreckel
Storage ring measurements … of H3+: a closer look
The relevance of H3+:
astronomer‘s periodic table
He
C
Si
Mg
Fe
N
O
Ne
S
Ar
DR 2010, Lake Tahoe, Aug19th 2010
Holger Kreckel
Storage ring measurements … of H3+: a closer look
The relevance of H3+:
engine of interstellar chemistry
CmHn
H3+ formation
C4H3+
C4H
H
e
C4H2+
H2
H2
C4
+
HC11N
+
+
C 4H
C3H2
e
C
e
C
C3H3
H2 + c.r.
H2+ + H2
HC9N
C3H
+
HC7N
H2
C3H+
HC5N
+
C
C3O
C2H2
e
+
H2C3O
C2H 4
e
CH3
e
e
OH
+
H3O
+
e
HC3N
Proton-hop reactions
e
+
C2H
C
e
+
e
CH 3OH2
CH3CO
+
+
H2
H2O
e
C2H5CNH
CH3CN
HCN
CH3+
CO
CH 3CNH
NH3
CH3NH2
N
H2
+
CH
H2O
+
CH5
CH3OH, e
e
CH 2CO
C
H3
+ 2
+
C2H 5
HCN H C N
3 3
CH4
H2CO
C2H 5OH
CH 3OCH 3
CH3OH
e
CO
H2++ eH3+ + H
H2CN
CH2
H2
H2
+
+
H2 O
H2
CH
C
+
OH
O
+
CO
N2
H2
+
H2
cosmic ray
H2
+
HCO
+
N2H
+
+ e
+ e
+ e
e
e
C2H5CN
CH3CN
CH2NH
CH3NH2
HCN
H3+ + X
XH+ +H2
DR 2010, Lake Tahoe, Aug19th 2010
Holger Kreckel
Storage ring measurements … of H3+: a closer look
The enigma of H3+ in diffuse clouds
Cosmic ray ionization rate
Steady State:

[H
]
2
[H3+] =
-]
[e
ke
DR rate coefficient
DR 2010, Lake Tahoe, Aug19th 2010
Holger Kreckel
Storage ring measurements … of H3+: a closer look
“Perceived” H3+ DR rate coefficient
H3+ DR rate coefficient at 300K
Leu, Biondi,
Johnsen (1973)
Stat. afterglow
Larsson et al. (1993)
Storage ring
McCall et al. (2003)
Storage ring
Amano (1988)
IR spectroscopy
10-7
Kreckel et al. (2005)
Storage ring
10-
Adams, Smith,
Alge(1984)
Flow. afterglow
8
Glosik et al.(2000-2009)
Stat. & flow. afterglow
10-9
10-10
Adams, Smith (1987)
Flow. afterglow
10-11
1970
1980
1990
2000
2010
year
DR 2010, Lake Tahoe, Aug19th 2010
Holger Kreckel
Storage ring measurements … of H3+: a closer look
Storage ring measurements: concept
Advantages
• radiative relaxation
of internal excitations
(rotation, vibration)
• direct measurement
• 100% detection efficiency
• high resolution
Problem
H 3+ !
• radiative relaxation
incomplete
DR 2010, Lake Tahoe, Aug19th 2010
Holger Kreckel
Storage ring measurements … of H3+: a closer look
Coulomb explosion results H3+
(1,00) theory
experimental
data (T > 2s)
(2,00)
theory
Vibrations decay within
the first 2s of storage
(0,00)
theory
Some rotational states
stay forever
experimental
data (T < 1ms)
Kreckel et al., PRA 66, 052509 (2002)
DR 2010, Lake Tahoe, Aug19th 2010
Holger Kreckel
Storage ring measurements … of H3+: a closer look
“Cold” ion sources
Gas inlet
2 atm
H2
5 cm
Solenoid
valve
Pinhole
flange/ground
electrode
-900 V
ring
electrode
CRYRING
2002
Supersonic
expansion
H3+
Cryogenic
ion trap
TSR
2004
DR 2010, Lake Tahoe, Aug19th 2010
Holger Kreckel
Storage ring measurements … of H3+: a closer look
Storage ring results with “cold” H3+ ion sources
● TSR electron temp.
kT┴=0.5 meV ~ 6K
kT||=25 μeV
trap temp. 13 K
Kreckel, PRL 95, 263201 (2005)
● CRYRING
Theory
Kokoouline
and Greene
kT┴= 2 meV
ion temp. 30-50 K
McCall, Nature
422, 500 (2003)
DR 2010, Lake Tahoe, Aug19th 2010
Holger Kreckel
Storage ring measurements … of H3+: a closer look
The holy grail: state specific measurements
+
H3+
rotational
levels
ortho
I = 3/2
+
para
I = 1/2
DR 2010, Lake Tahoe, Aug19th 2010
Holger Kreckel
Storage ring measurements … of H3+: a closer look
Nuclear spin effect: exp. and theory 2005
۰para H2
experiment
۰normal H2 kT┴=4 meV
theory
Greene et al.
- para
- ortho
Kreckel et. al, PRL 95, 263201 (2005)
DR 2010, Lake Tahoe, Aug19th 2010
Holger Kreckel
Storage ring measurements … of H3+: a closer look
Theory with more accurate resonance energies
S. Fonseca dos Santos et al., JCP 127, 124309 2007
DR 2010, Lake Tahoe, Aug19th 2010
Holger Kreckel
Storage ring measurements … of H3+: a closer look
Quantifying nuclear spin effects
Reduced
rate coeff.
B. Tom et al., JCP 130, 031101 2009
DR 2010, Lake Tahoe, Aug19th 2010
Holger Kreckel
Storage ring measurements … of H3+: a closer look
Piezo expansion source
plunger
locking nut
discharge
electrode
skimmer
high pressure
H2 reservoir
low pressure
pinhole
6 cm
piezo actuator
DR 2010, Lake Tahoe, Aug19th 2010
Holger Kreckel
Storage ring measurements … of H3+: a closer look
Cavity ring down measurements at UIUC
Difference frequency generation: 3.67 μm
DR 2010, Lake Tahoe, Aug19th 2010
Holger Kreckel
Storage ring measurements … of H3+: a closer look
Transitions observed
HG
DR 2010, Lake Tahoe, Aug19th 2010
Holger Kreckel
Storage ring measurements … of H3+: a closer look
Rotational temperature
pure H2 discharge, 2bar
Trot=110 K
No vibrations found!
1:5 H2:Argon discharge, 2bar
Trot=180 K
DR 2010, Lake Tahoe, Aug19th 2010
Holger Kreckel
Storage ring measurements … of H3+: a closer look
Nuclear spin manipulation
ortho H3+
1:5 n-H2 : Argon mixture
1:5 p-H2 : Argon mixture
para H3+
para H3+
p-H3+ fraction p3= (47.9 ± 2) %
p-H3+ fraction p3= (70.8 ± 2) %
DR 2010, Lake Tahoe, Aug19th 2010
Holger Kreckel
Storage ring measurements … of H3+: a closer look
DR measurements at TSR
UI Champaign-Urbana
MPI-K Heidelberg
Test Storage Ring
DR 2010, Lake Tahoe, Aug19th 2010
Holger Kreckel
Storage ring measurements … of H3+: a closer look
Absolute scale of the rate coefficient
electron
density
electron beam
switched off
electron target length
storage ring circumference
DR 2010, Lake Tahoe, Aug19th 2010
Holger Kreckel
Storage ring measurements … of H3+: a closer look
Comparison to CRYRING 2002
TSR 2009 (n-H2:Ar 1:5)
CRYRING 2002 (n-H2)
DR 2010, Lake Tahoe, Aug19th 2010
Holger Kreckel
Storage ring measurements … of H3+: a closer look
Rotational temperature: imaging basics
H2+ + ebeam vel.
δt
d
detector
1m
P(D)
3-dimensional imaging, point source
d ~ √Ek
2-dimensional imaging, point source
2-dimensional imaging, extended source
DR 2010, Lake Tahoe, Aug19th 2010
Holger Kreckel
Storage ring measurements … of H3+: a closer look
2-dimensional imaging of the 3-body breakup
ne(cooler) = 1.4 x 107 cm-3
ne(target) = 1.34 x 106 cm-3
H3+ + e-
H+H+H
expected
KER = 4.79 eV
DR 2010, Lake Tahoe, Aug19th 2010
Holger Kreckel
Storage ring measurements … of H3+: a closer look
2-dimensional imaging of the 3-body breakup
H3+ + erotational
temperatures
(uncertainties ~ 200 K)
950 K
450 K
200 K
H+H+H
DR 2010, Lake Tahoe, Aug19th 2010
Holger Kreckel
Storage ring measurements … of H3+: a closer look
Piezo source extraction potentials
DR 2010, Lake Tahoe, Aug19th 2010
Holger Kreckel
Storage ring measurements … of H3+: a closer look
Conditions on-axis downstream of the nozzle
skimmer
Collisional
heating during
Ion extraction?
DR 2010, Lake Tahoe, Aug19th 2010
Holger Kreckel
Storage ring measurements … of H3+: a closer look
Detailed comparison
of the (reduced) rate coefficient
TSR / 22-pole trap 2007
CRYRING / Solenoid 2002
TSR / piezo 2009
DR 2010, Lake Tahoe, Aug19th 2010
Holger Kreckel
Storage ring measurements … of H3+: a closer look
Nuclear spin dependence of the rate coefficient
Reduced
rate coeff.
1:5 n-H2 : Argon mixture
1:5 p-H2 : Argon mixture
Extrapolation:
100% ortho H3+
100% para H3+
p3= (47.9 ± 2) %
p3= (70.8 ± 2) %
DR 2010, Lake Tahoe, Aug19th 2010
Holger Kreckel
Storage ring measurements … of H3+: a closer look
Summary
• While we measure a rotational temperature of 200K with CRD spectroscopy,
the stored H3+ ions are much hotter than the ion source.
• We observed clear differences between different ion sources
→ the heating is probably happening prior to injection into the ring .
• We observed for the first time detailed structures in
the rate coefficients for ortho-H3+ and para-H3+ at low energies.
Results: Kreckel et al., submitted to PRA
Petrignani et al., in preparation
The holy grail?
Still out there …
DR 2010, Lake Tahoe, Aug19th 2010
Holger Kreckel
Storage ring measurements … of H3+: a closer look
Perspectives:
the case to continue the quest
It is crucial to understand:
H3+ + H2 and
H3+ (J=1,K=0,1) + e-
Kyle N. Crabtree et al., to be published
DR 2010, Lake Tahoe, Aug19th 2010
Holger Kreckel
Storage ring measurements … of H3+: a closer look
Collaboration
TSR
Group
University
of Illinois
Kyle N. Crabtree
Brian A. Tom
Benjamin J. McCall
Oldřich Novotny*
Annemieke Petrignani
Max H. Berg
Dennis Bing
Manfred Grieser
Claude Krantz
Michael Lestinsky*
Mario B. Mendes
Christian Nordhorn
Roland Repnow
Julia Stützel
Andreas Wolf
Weizmann
Institute
Henrik Buhr
Stockholm
University
Richard Thomas
*Columbia University, NY
Funding:
National
Science
Foundation
Max-Planck
Society
German-Israeli
Foundation
Eurppean
Comission
DR 2010, Lake Tahoe, Aug19th 2010
Holger Kreckel
Storage ring measurements … of H3+: a closer look