Víctor J. Herrero and Isabel Tanarro - Digital CSICdigital.csic.es/bitstream/10261/88448/1/2013-Toulouse... · 2016. 2. 18. · Co-authors José Luis Doménech Maite Cueto Esther

Plasma kinetics and spectroscopic studies in glow discharges of

mixtures of hydrogen with simple molecules

Víctor J. Herrero and Isabel Tanarro

Instituto de Estructura de la Materia, CSIC, Madrid, Spain

[email protected]@csic.es

Dusty Plasmas and Cosmic Dust. Toulouse, June 2013

Co-authors José Luis Doménech Maite Cueto Esther Carrasco Belén Maté Miguel Jiménez José Cernicharo et al.

Funding: MCINN (Spain) under grants CSD2009-00038, FIS2010-16455, FIS2012-28175, AYA2009-07304


(*) Carrasco et al. PCCP 2011, 13, 19561; 2013, 15, 1699; PPCF 2012, 54, 124019

(*)1. Proton transfer chains

2. Spectroscopy and detection of NH3D+ in space

3. Dusty plasmas (preliminary measurements)

Outline


Molecular ions in the interstellar medium (ISM) in order of first detection

Cations CH+ , HCO+ , N2H+, HCS+ HOCO+, HOC+,

HCNH+, H3O+, SO+, CO+, HC3NH+, H3+,

H2COH+, CF+, H2O+ ,OH+ , H2Cl+, C14H10+

, SH+, HCl+

Anions OCN-, C6H-, C4H-, C8H-, C3N- , C5N- , CN- ,

Most cations are protonated species


Model of ions in a protostellar envelope

Neutrals n(X)/n(H2): CO ~10-4, H2O ~ 10-5, NH3 ~ 10-7

T (K)

30100200400

Rodgers & Charnley ApJ 2003

Distance to star center

H3O+

NH4+


Experimental details

Tanarro et al., J.Phys.Chem.A 111, 9003 (2007) Méndez et al, Phys.Chem.Chem.Phys., 12, 4239 (2010)

Hollow Cathode reactor (10 cm Φ 30 cm length)

Gases: H2, D2, N2, O2, air P= 8 Pa (n ~ 2×1015cm-3) T~ 300 K Residence time 0.75 s Discharge: 150 mA, 400 V Homogeneous glow, E ~ 0 V/m Sheath ~ 1-2 cm ne~ (2-3)×1010 cm-3, Te~ 3-4 eV Ionization degree ~ 10-5


Cold Plasma Laboratory, IEM, CSICDusty Plasmas and Cosmic Dust. Toulouse, June 2013

H2/N2 plasma

0 ,0

0 ,1

0 ,2

0 ,3

0 ,4

0 ,5

0 ,6

P rotonated ions

Rel

ativ

e co

ncen

tratio

n N H +4

N 2H +

H +3

0 ,00 0 ,03 0 ,06 0 ,09 0 ,12

10 -2

10 -1

10 0

N eutra lsR

elat

ive

conc

entra

tion

F rac tion o f N 2 (d ischa rge o ff)

N H 3

N 2

H 2

P= 8 PaT= 300 K


Main protonation reactions1) H3

++ N2→ N2H++H2) H3

++ NH3→ NH4++H

3) N2H++ NH3→ NH4++N2

10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 101

109

1010

1011

NH+3

NH+4

H2

N2

N2H+

Con

cent

ratio

ns (c

m-3)

H+3

Con

cent

ratio

ns (c

m-3)

Time (s)

10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 101

1012

1013

1014

1015

NH3

0,0

0,1

0,2

0,3

0,4

0,5

0,6

Fra

ctio

n of

H3+

Fraction of N2

Symbols: Experiment : Full Model : Model without R1

0,0

0,1

0,2

0,3

0,4

0,5

0,6

Fra

ctio

n of

NH

4+0,00 0,02 0,04 0,06 0,08 0,10 0,12

0,0

0,1

0,2

0,3

0,4

0,5

0,6

Fra

ctio

n of

N2H

+

H3+

N2H+

NH4+

3)

0.00 0.02 0.04 0.06 0.08 0.10

Fraction of N2

Kinetic Model Results


H2/N2(11%))

H2/air plasmas 0.0

0 .1

0 .2

0 .3

0 .4

0 .5

0 .6

Protonated ions

N H +4

H 3O +

N 2H +

H +3

Rel

ativ

e co

ncen

tratio

n pr

oton

ated

ions

0 .03 0 .06 0 .09 0 .12 0.15 0.18

10 -2

10 -1

10 0

N eutralsR

elat

ive

conc

entra

tion

F rac tion o f a ir (d ischarge o ff)

H 2O

O 2N H 3

N 2

H 2


Hierarchy of protonated ions

Molecule X Proton affinity of X (kJ mol)

Protonatedion, XH+

k (T=300 K) XH++NH3→NH4

++X (cm3 s-1)

NH3 853.6 NH4+ --------

H2O 691 H3O+ 2.2310-9

N2 493.8 N2H+ 2.3010-9

H2 422.3 H3+ 4.4010-9

O2 421 HO2+ 1.810-9X

0.0

0.1

0.2

0.3

0.4

0.5

0.6

Protonated ions

NH+4

H3O+

N2H+

H+3

Rel

ativ

e co

ncen

tratio

n pr

oton

ated

ions

0.03 0.06 0.09 0.12 0.15 0.18

10-2

10-1

100

Neutrals

Rel

ativ

e co

ncen

tratio

n

Fraction of air (discharge off)

H2O

O2NH3

N2

H2


(*)

* Cernicharo et al. ApJL 2013, 771, L10; Doménech et al. ApJL 2013, 771, 11

1. Proton transfer chains



Outline


Deuterated ammonium

Deuterium enrichment favored in cold environments

Ammonium precursor of ammonia in cold clouds:

N+→ NH+ → NH2+ → NH3

+→ NH4+→ NH3 + H

All deuterated derivatives of NH3 have been detected

Spectroscopic data for NH3D+ available 10 - 00 rotational transition: 262807 9 MHz (3)(Nagaka & Amano Can. J. Phys. 1986 from IR spectrum of 4band)

H2 H2 H2 H2e-


NH3D+?

Spectrum toward Orion-IRc-2. Orion line survey with 30 m IRAM telescope

(Tercero et al. A&A 2010, 2011)

U 262816.7 MHz

Nagaka &Amano

Spectrum toward B1–bS(all D derivatives of NH3 present)

262816.73 MHz

New measuerementsCernicharo et al.

Refine spectroscopy of NH3D+ ?


Difference-frequency laser IR spectrometer


F1= 14.4 kHz; F2=5.5 kHz; F3=F1+F2= 19.7 kHz

Multipass hollow cathode discharge cell

White cell ~ 9 m optical path with water cooled copper cathode


Deuterated ions in N2/H2 plasma

0 5 10 15 20 25 300.00

0.05

0.10

0.15

0.20

0.25

N2+

N2D+

N2H+

N+NH+NH+

2NHD+

3

NH2D+2

NH+3

H+3

D2H+

DH+2H+

2H+

NH+4

D+3

Nor

mal

ized

Ion

Con

cent

ratio

ns

Mass (a.m.u.)

H2(7.4 Pa)+D2(2.4 Pa)+N2(2.4 Pa)150 mA

NH3D+

Total ion density ~ 3 × 10-10 cm-3


Levels involved in the 4 band of NH3D+

J

2

1

0

K=0

10 – 00 transition


NH4+ Schafer, Saykally, Robiette 1984, JChemPhys 80, 3969

This work

Both this work and N&A

The 4 band of NH3D+


Portion of the 4 band of NH3D+

Lines with an asterisk correspond to NH4+

Discharge:V=300 VI= 200 mAf=5.5 kHz

Plasma precursor:NH3:D2 (2:3)P= 34 PaT~ 300 K


Fit of the new 4 spectrum of NH3D+

Main improvements:

1. Absolute frequencies

2. More lines

JK =10 – 00 (MHz) ± 3σ 262807 ± 9262817 ± 6


NH3D+

Spectrum toward Orion-IRc-2. Orion line survey with 30 m IRAM telescope (Tercero et al. A&A, 2010,2011)

Nagaka &Amano

NH3D+ (-4- this work)3


1. Proton transfer chains



Outline


Inductively coupledRF discharge


CH4/He mixture

P=30 PaCH4:He (2:1)

Inside the coil Outside the coil

250 μm

Dust & films

Deposition 120 min


IR spectra of deposits in CH4/He plasma

3000 2500 2000 1500 1000

0,0

0,1

0,2

0,3

0,4

0,5

abso

rban

ce

wavenumber / cm-1

Reflectance normal incidence

CH stretch C=C stretch

CHx bend

AromaticsAliphatics

Outside the coil

Inside the coil

3.4 µm 6.9 µm6.2 µm

11.3 µm


Comparison with previous data: The 3.4 µm band

Kovačević et al. ApJ 2005RF Capacitive discharge13.56 MHz; 10-50 WP=10 PaAr:C2H2 =8:0.5 sccm

This workInside the coil


CH4 / N2 mixtureP=30 PaCH4:N2 (2:1)

Inside the coilOutside the coil

Deposition 120 min


IR spectra of deposits in CH4/N2 plasma

3000 2000 1000

0,0

0,3

0,6

0,9

abso

rban

ce

wavenumber / cm-1


NHstretch

CHstretch

CNstretch

C=NC=C

stretch

CHxbend


Comparison with previous work. Tholins


3000 2000 1000

0,0

0,3

0,6

0,9

1,2

1,5

1,8

abso

rban

ce

wavenumber / cm-1


Imanaka et al.Icarus 2004

X 4

Deposit:ICP plasma100W126 PaN2:CH4 (9:1)

This work

FIN


For pressures > 2 Pa ion-molecule chemistry dominates over electron impact

Ion distributions: Chemistry vs. electron impact in H2 plasmas

1 2 30,0

0,3

0,6

0,9

H+2

H+

H+3

Rel

ativ

e Io

n C

onc.

H2 (Pa)

1 2 3

4

6

8

T e (e

V)

H2 (Pa)

Te4 5 6 7 810-10

10-9

H2 H+2H+

3+ H

H2+eH+2+2e

Te

k (c

m3 s-1

)

(eV)


H2/N2 Plasma

1 2 30.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6C

once

ntra

tion

/1015

(cm

-3)

NH+2

Con

cent

ratio

n /1

010 (c

m-3)

H+

H+3

H+2

14 16 18

(b)

Experiment Model

Mass (a.m.u.)

NH+3

N+

NH+4

N2H+

H H2N NH NH2 NH3

N2

(a)

28 29 30

0.00

0.05

0.10

0.15

1.5

Good global agreement model-- measurements

Protonated ions dominant

6% N2

N2 /H2 plasma kinetic model

H2/O2 plasmas

Neutrals H2O, formed at the walls,

is more abundant than the O2 precursor

Protonated ions H3O+ always dominant Main protonation reaction:

H3++ H2O→ H3O++H2

Hardly any HO2+

0.0

0.1

0.2

0.3

0.4

0.7

0.8

Protonated ions

Rel

ativ

e co

ncen

tratio

n

H3O+

O2H+

H+3

0.00 0.03 0.06 0.09 0.12 0.15

10-2

10-1

100

Neutrals

Rel

ativ

e co

ncen

tratio

n

Fraction of O2 (discharge off)

H2O

O2

H2

HO2+

IR spectrometer: difference frequency mixing I2 locked Ar+ laser + Ring dye laser Spectral purity: ~1:108 (2 MHz) Accuracy: ~1 MHz Wavemeter for the dye laser (10 MHz) Tunability 2.2 – 4.2 µm

(2300-4500 cm-1) 1.2 cm-1 continuous scan Sensitivity: ~1:104

1 µW vs. 10-5 NEP of InSb First setup: Alan Pine (JOSA1976) Oka, Amano, Nesbitt…

J. L. Doménech et al. Detection of Ammonium in Space. WF05 68th

Int. Symposium on Molecular Spectroscopy. Columbus 2013Dusty Plasmas and Cosmic

Dust. Toulouse, June 2013

J. L. Doménech et al. Detection of Ammonium in Space. WF05 68th Int.

Symposium on Molecular Spectroscopy. Columbus 2013

The discharge cell

• Hollow-cathode discharge• Design Foster &

McKellar(JCP1984)• 380 V, 200 mA• White cell ~9 m inside the

cathode• Discharge modulated at 5.5 kHz• IR AM-modulated at 14.2 kHz• Lock-in detection at 19.7 kHz

Precursors:NH3, D2, 2:3Total pressure 0.34 mbar


J. L. Doménech et al. Detection of Ammonium in Space. WF05 68th Int. Symposium on Molecular Spectroscopy. Columbus 2013

This work Nakanaga & Amano (1986)

Lines marked with * belong to NH4

+

Rather similar S/NDusty Plasmas and Cosmic Dust. Toulouse, June 2013

Energy levels of prolate symmetric top

Documents

Víctor J. Herrero and Isabel Tanarro - Digital CSICdigital.csic.es/bitstream/10261/88448/1/2013-Toulouse... · 2016. 2. 18. · Co-authors José Luis Doménech Maite Cueto Esther