Supersonic Free-jet Quantum Cascade Laser Supersonic Free-jet Quantum Cascade Laser Measurements of Measurements of 44 for CF for CF33

3535Cl and CFCl and CF333737Cl and Cl and

FTS Measurements from 450 to 1260 cmFTS Measurements from 450 to 1260 cm-1-1

Supersonic Free-jet Quantum Cascade Laser Supersonic Free-jet Quantum Cascade Laser Measurements of Measurements of 44 for CF for CF33

3535Cl and CFCl and CF333737Cl and Cl and

FTS Measurements from 450 to 1260 cmFTS Measurements from 450 to 1260 cm-1-1

June 20, 2008

James F. Kelly, Thomas A. Blake, Robert L. SamsPacific Northwest National Laboratory

Richland, WA

Arthur MakiMill Creek, WA

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Line-of-Sight Free Space CommunicationsLine-of-Sight Free Space CommunicationsLine-of-Sight Free Space CommunicationsLine-of-Sight Free Space Communications

quantumcascade

laser atmosphere, fog, aerosols, turbulence> km distances

gas cell

detector

Lock laser on side of transition.Apply blue then red (“1”) or red then blue (“0”) FM chirp for bit transmission.Use gas to demodulate laser signal: FM to AM conversion at detector.Use laser wavelength that is less susceptible to atmospheric scattering effects.Provides secure, line-of-sight communications.Need a strong absorber in atmospheric window with sharp rovibrational transitions.

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Fundamental Vibrational States (cm-1) of CF3Cl

Fundamental CF335Cl CF3

37Cl

1 (a1) 1108.356 1108.026

2 (a1) 783.362 782.208

3 (a1) 476.968 469.165

4 (e) 1216.758 1216.720

5 (e) 561.109 560.822

6 (e) 347.2

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Ground State Constants (cm-1) of CF3Cl

CF335Cl CF3

37ClA 0.191 3a 0.191 3a

B 0.111 263 458b 0.108 461 01b

DJ 108 1.843 98b 1.759 3b

DJK108 6.929 7b 6.724 4b

DK 108 4.123a 4.123a

a) Amrein, et al. Chem. Phys. Lett. 139 82-88 (1987).

b) Carpenter, et al. J. Mol. Spec. 93 286-306 (1982).

Vibrational assignments checked against ground state combination differences, F2.

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ExperimentExperimentExperimentExperiment

Chlorotrifluoromethane (CF3Cl, Freon-13) purchased from SynQuest Labs.

Quantum cascade laser, pulsed, slit-jet molecular beam Laser covers 1215.8 to 1220.6 cm-1 of 4 band. 0.1% CF3Cl in Ar, backing pressure 100 to 1000 Torr. 12 cm x 200 m, 7.5 mS pulse duration at 2.88 Hz.

Fourier transform spectra of CF3Cl 1, 25, 4 bands: 20 cm path, 25 & -67 °C

0.0018 cm-1 resolution. 2, 23 bands: 20 cm path, 25 °C

3.2 m path, 22 °C0.0013 cm-1 resolution.

5 band: 9.6 m, 22.4 m path, 22 °C 0.004 cm-1 resolution.

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7

8

9

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Term Value Expression:

F(J,k,l) = G(v,l ) + Bv J(J+1) + (Av Bv) k2 kl [ 2Av Jv J(J+1) k

vk2

JJv J2(J+1)2 JK

v J(J+1)k2 KKvk4]

DJv J2(J+1)2 DJK

v J(J+1)k2 DKv k4

+ HJvJ3(J+1)3 + HJK

vJ2(J+1)2k2 + HKJvJ(J+1)k4 + HK

vk6

l-type Resonance Hamiltonian:

W2,2 = v4, J, k, l | H/hc | v4, J, k 2, l 2

= ¼ {q4 + qJ4J(J+1) + qK

4 [k2 + (k2)2 ]} {(v4+1)2 (l 1)2}½

{[ J (J + 1) k (k 1)][ J (J + 1) (k 1)(k 2)]}½

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44 Band Band44 Band Band

Use work of Amrein et al. Chem. Phys. Lett. 139 82-88 (1987) as starting point: J ≤ 20, K ≤ 20.Jet spectra improve assignment and fit in the Q-branch region.Present FTS measurements extend out to J = 76 and K = 49.Intensity alternation and ground state combinations used to verify assignments.

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Rovibrational Constants (cm-1) for the 4 Band

CF335Cl CF3

37Cl 0 1216.758 284(12) 1216.719 91(3)A103 0.751 04(4) 0.752 52(21)B103 0.003 797(21) 0.005 89(14)DJ108 0.061 3(7) 0.066(11)DJK108 0.203 8(24) [0.20]DK108 0.218 1(32) [0.22]A 0.151 052 4(4) 0.151 035 6(20)J106 0.338 2(5) 0.303 7(62)K106 0.094 7(9) [0.095]q4103 0.195 38(11) 0.181 54(24)qJ

4108 0.144(4) [0.14]Jet spectrum:

No. lines 339 231Rms dev. 0.00022 0.00023

FTS spectrum:Jmax 76 41Kmax 49 20No. of lines 4060 559Rms. Dev. 0.00020 0.00021

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a. PR3(10) 1219.4067 cm-1

b. RR6(16) 1219.4288 cm-1

c. RR3(14) 1219.4344 cm-1

d. RR0(12) 1219.4454 cm-1

P0 = 100 Torr0.1% CF3Cl in Ar12 cm x 200 m slit7.5 mS gas pulse duration2.88 Hz gas pulse rate0.038 cm-1/mS laser sweepSingle sweepLaser power 45 mW

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11 and 2 and 255 Coupling Term Coupling Term11 and 2 and 255 Coupling Term Coupling Term

v1, v5, J, k, l5 | H/hc | v11, v5+2, J, k2, l52

= {c2,2 + ck2,2 [k2+(k 2)2]}

{[J(J+1) k(k1)][J(J+1) (k1)(k2)]}½

Crossing levels:J = 29, K = 18 level of 1 and J = 29, K = 16, l = -2 of 25

J = 46, K = 19 level of 1 and J = 46, K = 17, l = -2 of 25

…and higher K values.

Coupling through a k = ±2, l = ±2 matrix element …

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11 Band Band11 Band Band

Giorgianni et al. J. Mol. Spec. 130 183-192 (1988) extended diode laser measurements out to J = 65 for the 1 band.

Our measurements go to J = 86 and K = 33. High density of lines and perturbations prevented assignments and fitting of higher transitions.No Q-branch lines used in fit. Only well resolved P- and R-branch lines were included in fit. Transitions with K < 5 not included in fit.

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2255 Band Band2255 Band Band

25 consists of a parallel band with l = 0 and a perpendicular band with l = 0 and l = ±2.The l = ±2 levels are too weak to see.

The perturbations of 1 = 1 are caused by an avoided crossing with the kl < 0 rotational manifold of 25.

Only R-branch transitions were observed because the P-branch transitions overlapped with 1 band.

Fit of the A component indicated that the E component is ~1 cm-1 lower.

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Rovibrational Constants (cm-1) for CF335Cl

1 250 25

2

0 1108.356 41(4) 1122.854 15(6) 1121.785(10)A103 0.380 23(28) 0.378 76(40) [0.37876]B103 0.566 97(5) 0.095 05(10) [0.09505]DJ108 0.103 4(18) 0.233 0(35) [0.233]DJK108 0.483(11) 0.543(18) [0.543]DK108 1.92(6) 0.211(46) [0.211]HJ1012 0.062 5(19) HJK1012 0.439(16) HKJ 1012 2.50(8) HK1012 15.2(4) A 0.131 28(14)q5104 [1.34]c2,2104 0.211(5)cK

2,2107 0.093(6)

No. of lines 2746 514Rms dev. 0.00022 0.00025

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Rovibrational Constants (cm-1) for CF337Cl

1 250 25

2

0 1108.025 93(8) 1122.299 64(21) 1121.214 8(12)A103 0.387 58(41) 0.385 7(12) [0.3857]B103 0.544 35(15) 0.088 02(32) [0.08802]DJ108 0.123(7) [0.245] [0.245]DJK108 0.254(32) [0.596] [0.596]DK108 3.04(5) [0.163] [0.163]HJ1012 [0.06] HJK1012 [0.43] HKJ 1012 [2.5] HK1012 [15.2] A [0.131 28]q5104 [1.34]c2,2104 [0.211]cK

2,2107 [0.093]

No. of lines 711 34Rms dev. 0.00025 0.00041

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33 State and 2 State and 23 3 BandBand33 State and 2 State and 23 3 BandBand

3 band is very weak.

Burger et al. J. Mol. Spec. 93 55-73 (1982) gives band origin of 3 at 476.973(7) cm-1 from 0.04 cm-1 resolution spectra.

Use the 1 – 3 difference band and 2 + 3 – 3 hot band to determine 3 state constants.

For the 23 band the K structure in the P- and R-branches is sharply peaked; assume the maximum is at K = 2.For the Q-branch the most intense transitions are K = J; assume peak is highest K value divisible by 3.

23 band of CF337Cl band was too weak to get full

assignment, but could determine band origin.

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Rovibrational Constants (cm-1) for 3 and 23

CF335Cl CF3

37Cl

23 3 23 3

0 952.406 16(8)a 476.967 54(7) 936.943 61(21) 469.164 85(11)A103 0.060 59(25) 0.029 28(28) [0.055 0] 0.027 9(14)B103 0.140 936(39) 0.067 30(6) 0.135 40(19) 0.064 56(11)DJ108 [0.072] 0.036 9(11) [0.072] 0.050 1(23)DJK108 0.349(33) 0.126(8) [0.36] [0.12]DK108 0.334(32) 0.003(30) [0.32] [0.00]

No. of lines 215 710 41 129Rms. Dev. 0.00028 0.00025 0.00041 0.00029

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22 Band Band22 Band BandPrevious results from diode laser measurements of Baldacchini et al. J. Mol. Spec. 130 337-343 (1988).K structure in R-branch not resolved; assume K = 2 for these transitions.K structure in P-branch partially resolved down to J = 25 for CF3

35Cl and J = 50 for CF337Cl.

For resolved J structure in P-branch only strong transitions up to K = 48 with K divisible by 3 were used in fit.Low-J Q-branch transitions were assumed to be the largest K value possible divisible by 3.

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Rovibrational constants (cm-1) for 2 and 2+33

CF335Cl CF3

37Cl 2 2+33 2

0 783.362 065(35) 781.773 09(6) 782.208 49(7)A103 0.156 530(52) 0.156 52(16) 0.156 54(9)B103 0.168 814(15) 0.170 377(14) 0.163 071(17)DJ1010 0.073(12) [0.073] [0.073]DJK1010 0.99(14) [0.99] [0.99]DK1010 4.31(14) [4.31] [4.31]

No. of lines 841 175 268Rms. Dev. 0.00020 0.00026 0.00032

25

26

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55 Band Band55 Band Band

RQ0-branch is sharper than other Q-branches because of large q5 value.

Band center agrees with results of Burger et al. Spectrochim. Acta 39A 985-992 (1983); B5 and q5 values agree with -wave results of Carpenter et al. J. Mol. Spec. 93 286-306 (1982).Most Q-branches resolved for J > 20. P- and R-branches are resolved up to kl = +16.High density of lines made it difficult to assign the CF3

37Cl transitions.

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Rovibrational Constants (cm-1) for 5

CF335Cl CF3

37Cl

0 561.108 935(12) 560.822 21(29)A103 0.184 774(25) 0.190 5(6)B103 [0.076 442 9]c 0.076 67(28)DJ108 0.011 68(16) 0.056(7)DJK108 0.002 26(90) [0.0022]DK108 0.082 92(92) [0.082]A 0.140 514 79(59) 0.141 041 2(35)J106 0.016 5(10) [0.0165]K106 0.406 1(11) [0.406]JJ1012 0.85(18) [0.85]JK1012 1.27(27) [1.27]q5104 [0.946 718 28] [0.946718]qJ109 0.038(11) [0.038]qK109 15.1(15) [15.1]

Jmax 86 66Kmax 70 28No. of lines 5653 259Rms dev. 0.00025 0.00052

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SummarySummarySummarySummary

Improved spectroscopic constants for the 4 band using combined QC-laser and jet spectra. Extend J and K values in FTS spectra.

Improved spectroscopic constants for the 1 and 25 bands. Extend J and K values in FTS spectra.

First rotationally resolved infrared measurement of 5 band.

Improved spectroscopic constants for 2 and 2 + 3 – 3 hot band. Extend J and K values in FTS spectra.

Use 1 – 3 and 2 + 3 – 3 to determine spectroscopic constants for 3 for the first time.