Submm Spectroscopy of N Radicals COST2016 N Isotopic Ratio in the Solar System (From Mumma & Charnley 2011)

Sub-millimetre spectroscopy of light nitrogen-bearing radicals and ions

Luca Bizzocchi

Center for Astrochemical Studies Max-Planck-Institut für extraterrestrische Physik, Garching, Germany

COST meeting – November 9, 2017– Copenhagen

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 N isotopic ratio in the Solar System (from Mumma & Charnley 2011)

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 N isotopic ratios in low-mass dense clouds

+ N2H NH3 HCN HNC CN 1200 NH2D

1000

800 L1544 N 15 /

N 600 14 L1689N PSN L1498

400 L1544 L1498 B1 B1 Earth L134 B1 L16293E B1

200 B1 L1521E L183 L1544 L1498 L1544 L1521F

Ikeda+2002, Lis+2010, Gerin+2009, Bizzocchi+2013, Adande+2015, Hily-Blant+2013, Milam & Charnley 2015,

Redaelli+ inprep

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 + Interlude: non-LTE modelling of N2H (1–0) in L1544

Observations 4 + N2H (1–0) Const. ab. model χ2 = 76.2

3 /K 2 mb T

0 4 0 4 8 12 16 −

3 4 4 F1 = 0 1 F1 = 2 1 F = 1 1 − − 1 − 3 3 2 2 2 1 1 1

0 0 0 3 2.5 2 1.5 1 4.5 5 5.5 6 6.5 7 7.5 8 11 11.5 12 12.5 13 13.5 − − − − − 1 vLSR / km s− Bizzocchi et al. (2013)

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 + Interlude: non-LTE modelling of N2H (1–0) in L183

Redaelli at al. in prep.

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 N isotopic ratios in low-mass dense clouds

+ N2H NH3 HCN HNC CN 1200 NH2D

1000

800 L1544 N 15 /

N 600 14 L1689N L1498 PSN L183

400 L1544 L1498 B1 B1 L134 B1 L16293E

Earth B1

200 B1 L1521E L183 L1544 L1498 L1544 L1521F

Ikeda+2002, Lis+2010, Gerin+2009, Bizzocchi+2013, Adande+2015, Hily-Blant+2013, Milam & Charnley 2015,

Redaelli+ inprep

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 N fractionation: summary

Observational evidences: large 14N/15N in cosmomaterials diﬀerent N reservoirs likely present large variations of 14N/15N in ISM too strong dependence on chemical carrier

Problems: observation data shortage biases N isotopic chemistry not perfectly understood complex relations with D- and 13C-fractionations

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 What about multiply substituted species?

very few detected so far 13 13 13 15 mainly C C- or D C-, ( NH2D) sensitive probes, provide tight constraint to models trace history, diﬀerent reservoirs weak features, line confusion problem high-sensitivity / spatial resolution ( ALMA) accurate RFs ( improve spectroscopic⇒ data base) ⇒ chemical networks, photo-dissociation rates etc.

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 Light nitrogen carriers in the ISM

availability of highly-precise∗ rest frequencies

“main” 15N 15N + D 15N +13C

NH3 yes yes yes — + N2H yes yes yes —

NH2 yes yes ? — NH yes yes ? — HCN yes yes yes yes HNC yes yes yes yes CN yes ? — ? ∗ directly measured in the lab

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 Sources of error for rest frequencies

incomplete description of rotational the energy manifold poor frequency coverage, coarse J, K sampling

slow convergence of the Hamiltonian expansion (critical for light species)

accidental resonances closeby vibrational (Fermi/Coriolis) or electronic (Renner–Teller) states

Measurements inaccuracies congested spectrum, complex HFS patterns, pressure shift

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 Radical and ions in the laboratory

3 Unstable in lab conditions (τ < 10− s) should be generated and studied “on-the-ﬂy”

Plasma techniques: DC, AC, mw- or rf-discharges low samples pressure 1–10 Pa low temperature ( 77∼ K practical limit) ∼ Diﬀerent plasma regimes: “Normal” discharge “Anomalous” discharge (magnetically enhanced / hollow cathode)

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 Plasma regimes

from “Industrial Plasma Engineering: Volume 2”

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 Glow discharge structure

from “wikipedia common”

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 Magnetically-enhanced “negative” glow discharge

Normal glow discharge

typical conditions: i 20 100 mA, ∆V < 1000 V ≈ −

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 Magnetically-enhanced “negative” glow discharge

Extended negative glow discharge

typical conditions: i 2 20 mA, ∆V 1000 5000 V force plasma into the≈ “abnormal”− discharge≈ conditions−

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 Magnetically-enhanced “negative” glow discharge

PROs: extends the plasma region with maximum ion density absence of E over long length (no drift) conﬁnement of molecular ions CONs: limitation in i/plasma density (“quasi” i ∆V ) coaxial B present = Zeeman eﬀect ∝ ⇒ B-enhanced: optimal for closed-shell molecular ions normal: used for radical and “high-current” unstable species

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 The discharge cell

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 The spectrometer

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 FM spectroscopy: lineshape analysis

FM techniques + 2nd harmonic detection The 2nd derivative of the actual spectral proﬁle is recorded Experimental proﬁle modelled as: Z ∞ iωT F2(ω) Re J2(mT )Φ(T )e dT ∝ 0

Voigt proﬁle function:

Φ(Γ, α , T ) = exp Γ T (α T )2/4 D − − D

αD is ﬁxed, the ﬁt yields ω0, Γ ,(+ empirical parameters)

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 doubly 15N-diazenylium

15N15NH+ and 15N15ND+

linear closed-shell ions (1Σ+) no detectable hyperﬁne structure greater intensity of the J = 1 0 line ← rotational spectrum analysed using simple Hamiltonian 2 4 6 Hrot = BJˆ DJˆ + HJˆ − produced in the “enhhanced” negative glow at 80 K via: 15 Ar + N2 + H2 (D2) ∆V = 3.5 kV, i = 4 10 mA −

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 15N15NH+ at 1 THz

experimental 15N15NH+ J = 13 12 model ← residuals 5 × detection signal / a.u.

1146732 1146737 1146742 1146747 1146752 Frequency / MHz

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 Pressure broadening and shift

Pressure broadening (Γ ) and pressure shift (s) coeﬃcients are related to the total population transfer rate among rotational states

Γ is = σ v n − h i σ P(k) ← X P(k) = 1 i, k S i, k0 f , k0 S∗ f , k − h | | ih | | i k0 Γ and s are experimental determinables

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 15N15NH+ J = 1 0 pressure shift ←

1 40 s = 3.13(12) MHz Torr− ν0 = 88264.0580(12) MHz

20 Frequency shift / kHz

0 0 5 10 15 Pressure / mTorr

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 15N15NH+ results

From Dore et al. 2017, A&A 604:A26

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 Recent attempt: 5 hr of integration on 05358-mm3, σ 2.5 mK, 14 15 + 15 + N NH / N2H > 40

Is 15N15NH+ detectable in ISM?

14 15 + 15 + N NH / N2H 20 100 predicted by the chemical model (Dore et al. 2017) ≈ − extreme 15N-enhanced HMSCs are “promising” candidates + 15 + (N2H /N NH 200, Fontani et al. 2015) ∼ line peak intensity up to 6 mK can be predicted for the J = 1 0 line ← 10 hr of telescope time at 0.2 km s 1 ∼ −

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 Is 15N15NH+ detectable in ISM?

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 D-15N-imidogen

15ND

3 diatomic radical with X Σ− ground state ﬁne + hyperﬁne structure, Hund’s b-type coupling scheme N + S = J

J + IN = F1

F1 + IH = F

produced in the positive glow at 85 K via: 15 ∼ Ar + N2 + D2 ∆V = 1 kV, i = 60 mA

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 15ND N = 2 1, J = 2.5 1.5 ← ←

1041.492 1041.497 1041.502 1041.507 1041.512 Frequency / GHz

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 Imidogen Dunham’s type analysis

Hˆ = Hˆvr + Hˆfs + Hˆhfs,el–nuc + Hˆhfs,rot–nuc

rotation-vibration Dunham’s constants: Y ( ω , ω x , B , α , D ,...) kl ≈ e e e e e e ﬁne structure constants: λ, γ, b, c, (+ vib-rot dependence terms) hyperﬁne structure constants: eQq, CI ,... (+ vib-rot dependence terms) mass-scaling relation:

α α l+k/2+β α 0 ∆MN N ∆MH H µ0 Xkl = Xkl + α δkl + α δkl MN MH µα

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 Imidogen: summary

new 15ND data recorded in the 487–1043 GHz range

multi-isotopologue analysis with 1349 data 4 species, rotational + IR lines, vmax = 6 66 parameters determined: 30(8) VR, 13(4) FS, 23 HFS

σﬁt = 0.873

1 N, J = 1, 0 0, 1 in the ALMA band 8 (σRF 0.04 km s ) ← ≈ − (Melosso et al. in prep)

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 D-15N-amidogen

15 ND2 and ND2

2 bent triatomic radicals with X B1 ground state ﬁne + hyperﬁne structure Hund’s b-type coupling scheme with two equivalent bosons

N + S = J , J + IN = F1 , F1 + ID = F

(ID = ID1 + ID2 )

spin statistics for NKa,Kc levels: K K = ee, oo ID = 1 (3 sublevels) a c → K K = eo, oe ID = 0, 2 (6 sublevels) a c →

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 ND2 N = 313 202 Ka,Kc ←

J = 3.5 ← 2.5 J = 2.5 ← 1.5

(b) (e) (a) (g)

(f)

1015.22 1015.23 1015.24 1015.25 1015.26 1016.38 1016.39 1016.4 1016.41 Frequency / GHz Frequency / GHz

15 positive glow at 200 K, Ar + ND3 discharge ∼ ∆V = 1 kV, i = 70 mA (200 s int. time)

Melosso et al. 2017, ApJS accepted

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 15 15 ND2 and ND simultaneous production

15 15 ND2, N = 312 303, J = 3.5 3.5( ) ND, N, J = 1, 0 0, 1 KaKc ← ← ∗ ←

*****

487.465 487.485 487.505 487.525 487.545 487.565 487.585 487.605 Frequency / GHz

15 positive glow at 200 K, Ar + ND3 discharge ∼ ∆V = 1 kV, i = 70 mA Melosso et al. in prep.

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 15 ND2: eﬀect of applied B

15 no B N2D NKaKc = 523 514, J = 5.5 5.5 ← ← small B (i 1 A) ∼ detection signal / a.u.

644540 644550 644560 644570 644580 Frequency / MHz

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 15 ND2 and ND2: results

ND2 64 new lines recorded in the 588–1131 GHz range first global fit with all available data (submm + FIR + MODR) 41 parameters determined, σfit = 0.87 “good” prediction capability up to 8 THz for (N 13, K 17) ≤ a ≤

15 ND2 174 new lines recorded in the 264–1051 GHz range 12 rotational transitions with N 5 and Ka 3 ≤ ≤ 32 parameters determined, σﬁt = 0.84 “good” rest frequency available in the submm and THz regimes

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 Light nitrogen carriers in the ISM. . . update

availability of highly-precise∗ rest frequencies

“main” 15N 15N + D 15N +13C

NH3 yes yes yes — + N2H yes yes yes —

NH2 yes yes yes— NH yes yes yes — HCN yes yes yes yes HNC yes yes yes yes CN yes ? — ? ∗ directly measured in the lab

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016 What’s next on this (sub-)topic?

15NHD: rotational spectrum unknown

C15N only a couple of ISM lines measured, never studied in the lab

H15NCO some MW measurements from H. Hocking et al. (1975) mm and submm lines aﬀected by large prediction uncertainties

Bizzocchi (CAS@MPE) Submm spectroscopy of N radicals COST2016