A precise study of the rotational spectrum of formaldehyde H212C16O,H213C16O,H212C18O,H213C18O

The rotational spectra of formaldehyde, H₂¹²C¹⁶O and its isotopic species H₂¹³C¹⁶O, H₂¹²C¹⁸O, and H₂¹³C¹⁸O have been investigated in the ground vibrational state in the frequency region between 8 and 460 GHz. For most cases in which measurements of the a-type R- and Q-branch transitions already existed the accuracy of the line position has been improved to about 10 kHz. For H₂¹²C¹⁶O and H₂¹³C¹⁶O a large number of ΔK_a = ±2 transitions were measured with similar accuracy. These new data when combined with all other available data and appropriate weightings lead to a set of ground state parameters which for the first time are compatible with infrared and ultraviolet data. The rotational constants (and 3σ standard deviations) obtained using Watson's A-reduced Hamiltonian are:

     

2.

Stark spectroscopy with the CO laser: The ν₂ fundamentals of H₂CO and D₂CO     

J.W.C. Johns  A.R.W. McKellar 《Journal of Molecular Spectroscopy》1973,48(2):354-371

The ν₂ (CO stretching) vibration-rotation bands of H₂CO and D₂CO near 5.8 μm have been studied using the technique of laser Stark spectroscopy. The following vibrational and rotational constants have been determined:

	H212C16O	H213C16O	H212C18O	H213C18O
A/MHz	281 970.572 (24)	281 993.258(135)	281 961.94 (39)	281 985.00 (93)
B/MHz	38 836.0456(13)	37 811.0887(25)	36 904.1693(66)	35 859.256(10)
C/MHz	34 002.2034(12)	33 213.9790(25)	32 511.5311(63)	31 697.868(10)

     

3.

The absorption spectrum of the Ag₂ molecule     

C.M Brown  M.L Ginter 《Journal of Molecular Spectroscopy》1978,69(1):25-36

The high dispersion absorption spectrum of the Ag₂ molecule has been photographed in the ～5300–1500-Å region. Observations include the previously reported A ← X, B ← X, C ← X, D ← X, and E ← X transitions and a new H ← X transition which occurs in the vacuum ultraviolet. Extensive spectral blending precluded detailed rotational analyses, but the band structures are consistent with $\text{ΔΩ}\text{= 0}$ and $\text{ΔΩ}\text{≥1}$ for D-X and C-X, respectively. The H state is perturbed and probably predissociated. The following molecular constants (in cm^?1) were obtained from fitting bandhead data to the usual expressions:

Constant	H2CO	D2CO	Unit
$\text{ν}{}_0$	1746.011	1701.620	cm?1
$\text{A′}$	281807.8 ± 6.	141696.6 ± 7.	MHz
$\text{B′}$	38608.7 ± 5.	32068.4 ± 7.	MHz
$\text{C′}$	33738.7 ± 3.	25998.6 ± 10.	MHz
μ″	2.328 ± 0.006	2.344 ± 0.006	Debye
μ′	2.344 ± 0.006	2.364 ± 0.005	Debye

     

4.

The rotation-inversion spectrum of ¹⁵NH₃     

M. Carlotti  A. Trombetti  B. Velino  J. Vrbancich 《Journal of Molecular Spectroscopy》1980,83(2):401-407

The rotation-inversion spectrum of ¹⁵NH₃ has been recorded between 38 and 280 cm^?1 with a resolution of about 0.03 cm^?1. By combining the present results with the inversion frequencies obtained by microwave spectroscopy, the following main rotational and centrifugal distortion constants were derived (in cm^?1):

State	Te	ωc	Xωt
X	0.0	192.0	0.58
B	35 838.6	151.8	0.87
C	37 631.6	171.0	0.84
D	39 014.5	168.2	1.20
E	40 159.9	146.1	1.58
H	58 273.1	165.9	2.46

     

5.

The ν₃ fundamental band of HDCO     

J.W.C Johns  A.R.W McKellar 《Journal of Molecular Spectroscopy》1977,64(2):327-339

The ν₃ fundamental band (CO stretch) of HDCO at 1724 cm^?1 has been studied using both conventional infrared absorption and CO laser Stark spectroscopy. In addition to the excited-state (v₃ = 1) rotational constants, improved constants for the ground state of HDCO have been obtained by combining previous microwave data with some infrared combination differences. The following constants were determined:

State	$\text{B}$	$\text{D}{}_{\mathrm{J}}$	$\text{D}{}_{\mathrm{JK}}$
$\text{v}{}_{\mathrm{<mtext>inv</mtext>}}\text{= 0}$	9.92235	0.0008493	?0.001575
$\text{v}{}_{\mathrm{<mtext>inv</mtext>}}\text{= 1}$	9.91742	0.0008336	?0.001532

     

6.

Laser Stark spectroscopy in the 10 μm region: The ν₃ bands of CH₃F     

S.M. Freund  G. Duxbury  M. Römheld  J.T. Tiedje  T. Oka 《Journal of Molecular Spectroscopy》1974,52(1):38-57

Laser Stark spectroscopy of the ν₃ band of CH₃F has been carried out using coincidences with the 9.4 μm band CO₂ laser lines. About 350 Stark resonances were measured for the ν₃ fundamental bands of ¹²CH₃F and ¹³CH₃F. About 30 of them were measured by using a Stark-Lamb dip technique to increase the resolution and the accuracy of the data. These Stark resonances, together with the recent results of infrared-microwave two-photon Lamb dip measurements, were analyzed to give the following vibration-rotation parameters and the dipole moments in the ν₃ state,

Constant	Ground state	$\text{v}{}_3\text{= 1}$ state	Units
$\text{ν}{}_0$		1724.267	cm?1
$\text{A}$	198 119.75	198 210.4	MHz
$\text{B}$	34 910.646	34 676.6	MHz
$\text{C}$	29 561.488	29 331.3	MHz
$\text{μ}{}_{\mathrm{a}}$	2.3302	2.3486	D
$\text{μ}{}_{\mathrm{b}}$	0.195	0.190	D

     

7.

Laser Stark spectroscopy of formaldehyde-d2: The Coriolis coupled ν4 and ν6 fundamentals     

Dewitt Coffey  Chikashi Yamada  Eizi Hirota 《Journal of Molecular Spectroscopy》1977,64(1):98-108

Using CO₂ and N₂O lasers, we have measured and assigned nineteen ν₄ and nine ν₆ rotation-vibration resonances of the type ΔM = 0 and M = J. These transitions were combined with the zero-field pure rotational spectra in order to determine the two fundamental vibrational frequencies, the rotational constants of both excited states, the Coriolis coupling constant, and the dipole moments of each of the three states. The ground-state rotational constants and centrifugal distortion constants were taken from a microwave study and the centrifugal distortion constants of the excited states were assumed equal to those of the ground state. The following results were obtained (standard deviations in parentheses):

	12CH3F	13CH3F
$\text{ν}{}_0$	1048.610767 (62)	1027.493191 (69)	cm?1
$\text{B}$	25197.57 ± 0.03	24542.07 ± 0.43	MHz
$\text{A - A}{}_0$	?294.09 ± 0.60	?288.81 ± 0.37	MHz
$\text{D}{}_{\mathrm{J}}$	55.5 ± 1.2	56 ± 12	kHz
$\text{D}{}_{\mathrm{JK}}$	575 ± 63	464 ± 24	kHz
μ	1.9054 ± 0.0006	1.9039 ± 0.0006	$\text{D}$

     

8.

High-resolution Fourier transform spectroscopy of the ν2 and ν3 fundamentals of nitrosyl fluoride,FNO     

S.C. Foster  J.W.C. Johns 《Journal of Molecular Spectroscopy》1984,103(1):176-186

The ν₂ and ν₃ fundamentals of FNO have been recorded with a Fourier transform spectrophotometer at an apodized resolution of approximately 0.004 cm^?1. The Fourier infrared data have been analyzed together with previous microwave data to yield improved molecular parameters for the (000) and (010) vibrational states and the first set of constants for the (001) state. The main results (in cm^?1) are

		$\text{ν}{}_4$		$\text{ν}{}_6$
$\text{ν}{}_0$		938.0345 (6)		989.2519 (18)		(cm?1)
$\text{A}$		139 579 (150)		143 323 (150)		(MHz)
$\text{B}$		31 873.6 (5)		32 379.5 (7)		(MHz)
$\text{C}$		26 242.9 (6)		25 994.4 (8)		(MHz)
$\text{ξ}{}_{64}{}^{\mathrm{(a)}}$			136 178 (770)			(MHz)
μ		2.319 (10)		2.347 (4)		(D)
μ(ground state)			2.3464 (8)			(D)

     

9.

Absorption spectrum of BS₂ at 4°K     

J.M. Brom  W. Weltner 《Journal of Molecular Spectroscopy》1973,45(1):82-98

BS₂, trapped in neon matrices at 4°K, exhibits extensive progressions in the A²Π_u ← X²Π_g and $\text{B}{}^2\text{Σ}{}_{\mathrm{u}}{}^{\mathrm{+}}\text{← X}{}^2\text{Π}{}_{\mathrm{g}}$ systems. From these transitions, those observed in the infrared, and a reinterpretation of gas-phase data, the following molecular constants (in solid neon) are obtained for linear symmetric ¹¹BS₂ (in cm^?1):

	Ground state	$\text{ν}{}_2$	$\text{ν}{}_3$
A	3.1751882 (17)	3.1861249 (12)	3.1958722 (15)
B	0.39508266 (12)	0.39407878 (14)	0.39211484 (14)
C	0.35051504 (11)	0.34899779 (16)	0.34747411 (14)
$\text{ν}{}_0$	0	765.3551 (4)	519.5980 (4)

     

10.

The 10.4 μm CO₂ laser Stark spectra of the ν₄ and the ν₉ bands of 1,1 difluoroethylene     

G Duxbury  H Herman 《Journal of Molecular Spectroscopy》1978,73(3):444-461

The ν₄ and the ν₉ bands of CF₂CH₂ have been studied using coincidences with the 10.4 μm band of the CO₂ laser and the 10.9 μm band of the N₂O laser. These resonances have been analyzed, together with recent microwave results, to give the following vibration-rotation parameters and dipole moments in the ν₄ and ν₉ states

$\text{B}{}^2\text{Σ}{}_{\mathrm{u}}{}^{\mathrm{+}}$	T0 = 24,072	$\text{ν}{}_1\text{= 516}$
$\text{A}{}^2\text{Π}{}_{\mathrm{u}}$	T0 = 13.766	$\text{ν}{}_1\text{= 506}$
	A0 = ?263	$\text{ν}{}_2\text{= 311}$
		$\text{ν}{}_3\text{= 1535}$
$\text{X}{}^2\text{Π}{}_{\mathrm{g}}$	A0 = ?440	$\text{ν}{}_1\text{= 510}$
		$\text{ν}{}_2\text{= ～120}$
		$\text{ν}{}_3\text{= 1015}$

     

11.

Acoustical measurement of solid state non-linearity: Application to CsCdF₃ and KZnF₃     

M.A. Breazeale  J. Philip  A. Zarembowitch  M. Fischer  Y. Gesland 《Journal of sound and vibration》1983,88(1):133-140

Combination of the results of two sets of measurements on the same crystalline samples of CsCdF₃ and KZnF₃ has made possible the evaluation of the third-order elastic (TOE) constants of these two fluoroperovskites. In the first technique the hydrostatic pressure dependence of the velocity of ultrasonic waves of different propagation and polarization directions has been measured to determine three linear combinations of TOE constants. In the second technique the fundamental and the second harmonic amplitudes of an initially sinusoidal longitudinal ultrasonic wave of finite amplitude propagating along the principal directions have been measured to determine three other linear combinations. Combination of the two sets of data leads to the following room temperature values of the TOE constants (in units of 10¹² dynes/cm²):

	$\text{ν}{}_4$ CF2CH2	$\text{ν}{}_9$ CF2CH2
$\text{ν}{}_0$	925.7692 (2)	953.8057 (2)	cm?1
$\text{A}$	10 971.99 (2)	11 026.918 (6)	MHz
$\text{B}$	10 414.98 (2)	10 436.381 (6)	MHz
$\text{C}$	5328.48 (2)	5346.100 (6)	MHz
μ	1.382 (1)	1.382 (1)	D
$\text{μ - μ}{}_0$	0.014 (2)	0.004 (1)	D

     

12.

The A1Π-X1Σ band system of CD+: Spectroscopic constants and isotope shifts     

A. Antić-Jovanović  V. Bojović  D.S. Pešić  S. Weniger 《Journal of Molecular Spectroscopy》1979,75(2):197-204

Six bands of the A¹Π-X¹Σ system of CD⁺ in the region 3800–4800 Å have been recorded in emission using an aluminum hollow-cathode discharge in the HeC₂H₂ mixture. From the vibrational and rotational analysis of the observed bands, the following constants (cm^?1) are obtained:

Sample	C111	C112	C114	C166	C123	C456
CsCdF3	?13·2	?4·55	?3·12	?0·69	+2·6	?3·8
KZnF3	?16·6	?4·75	?0·52	?1·79	+3·2	?6·87

     

13.

CO₂ laser Stark spectroscopy of the Coriolis-coupled ν₂ and ν₅ bands of CD₃Br     

Kensuke Harada  Keiichi Tanaka  Takehiko Tanaka 《Journal of Molecular Spectroscopy》1983,98(2):349-374

The ν₂ (CD₃ symmetrical deformation) and ν₅ (CD₃ degenerate deformation) fundamental bands of CD₃Br were studied by 9.4- and 10.4-μm CO₂ laser Stark spectroscopy. Stark resonances originating from 28 and 53 rovibrational transitions of the ν₂ and ν₅ bands, respectively, were assigned for each of the isotopic species, CD₃⁷⁹Br and CD₃⁸¹Br. These two bands were simultaneously analyzed with explicit inclusion of the ν₂-ν₅ Coriolis interaction, yielding precise molecular constants in the ν₂ and ν₅ excited states as well as the Coriolis coupling constant. The molecular constants obtained are consistent between the two isotopic species and are in good agreement with the results of high-resolution infrared studies. The band origins and dipole moments are

		$\text{T}{}_{00}$		$\text{ω}{}_{\mathrm{e}}$		$\text{ω}{}_{\mathrm{e}}\text{x}{}_{\mathrm{e}}$		$\text{ω}{}_{\mathrm{e}}\text{y}{}_{\mathrm{e}}$		$\text{B}{}_{\mathrm{e}}$		$\text{D}{}_{\mathrm{e}}\text{·10}{}^4$		$\text{α}{}_{\mathrm{e}}$
$\text{A}{}^1\text{Π}$		23 747.5		1367.3		60.6		0.75		6.428		5.7		0.388
$\text{X}{}^1\text{Σ}$		0		2035						7.650		4.1		0.190
				(2101.6)		(33.3)

     

14.

Fluorescence of the bromine molecules affer selective excitation by a single-mode krypton-lon laser     

G. De Vlieger  F. Claesens  H. Eisendrath 《Journal of Molecular Spectroscopy》1980,83(2):339-342

Optical-optical double-resonance (OODR) spectra of CaF are recorded, with reduced Doppler broadening, using two cw, single-mode dye lasers. Molecular constants for E²Σ⁺ and $\text{E′}{}^2\text{Π}$ are obtained from rotational analysis of the 0-0 and 1-0 E²Σ⁺-A²Π bands and the 0-0 $\text{E′}{}^2\text{Π}\text{-A}{}^2\text{Π}$ band, supplemented by fragmentary observations on the E′-A 0-1 and 1-1 bands:

		CD379Br		CD381Br
$\text{ν}{}_2$		991.396 82 (18)		991.388 46 (17)		cm?1
$\text{ν}{}_5$		1055.469 00 (12)		1055.466 32 (12)		cm?1
$\text{μ}{}_0$		1.830 42 (52)		1.829 84 (47)		D
$\text{μ}{}_2$		1.829 93 (48)		1.829 57 (46)		D
$\text{μ}{}_5$		1.832 23 (60)		1.831 19 (56)		D

     

15.

The microwave spectrum of the transient molecule chloro(sulphido)boron,ClBS: Substitution structure,dipole moment,quadrupole moment,and vibration-rotation analysis     

C. Kirby  H.W. Kroto 《Journal of Molecular Spectroscopy》1980,83(1):130-147

The rotational spectrum of the new reactive triatomic molecule chloro(sulphido)boron, ClBS, produced by the high-temperature reaction of gaseous dichloro disulphide, Cl₂S₂, and crystalline boron at ca. 1000°C was studied by microwave spectroscopy between 26.5 and 40 GHz. Ground state rotational constants have been obtained for 11 of the 12 isotopic variants involving ³⁵Cl, ³⁷Cl, ¹¹B, ¹⁰B, ³²S, ³³S, and ³⁴S; the isotopic shifts for the ground state lines of ³⁵Cl¹⁰B³⁴S from those of ³⁵Cl¹¹B³⁴S are too small and they are overlapped by the ¹¹B species. The abundance of rotational constant data has allowed a detailed comparison of various structure determination procedures to be made. The substitution method yields an extremely consistent ClS distance of 3.28715 ± 0.00005 Å. Application of the first moment condition allows the B atom, which lies close to the center of mass, to be quite accurately located. The resulting bond lengths are $\text{r(}\text{ClB}\text{) = 1.681 ± 0.001}\text{A}\text{?}$ and $\text{r(}\text{BS}\text{) = 1.606 ± 0.001}\text{A}\text{?}$. The more important derived spectroscopic parameters are:

				Main parameters
			$\text{E}{}^2\text{Σ}{}^{\mathrm{+}}$		$\text{E′}{}^2\text{Π}$
	$\text{T}{}_0$				34 171.218(2)	34 477.413(3)
	$\text{Δ}\text{G}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$				640.912(3)	668.991(24)
	$\text{B}{}_{\mathrm{<mtext>e</mtext>}}$		0.364393(18)		0.368423(50)
	$\text{α}{}_{\mathrm{<mtext>e</mtext>}}$		0.002266(18)		0.002375(50)
	$\text{A(0)}$			16.483(4)

     

16.

Microwave spectroscopy of the ν₈-ν₆ band of diacetylene     

Keiji Matsumura  Tohru Etoh  Takehiko Tanaka 《Journal of Molecular Spectroscopy》1981,90(1):106-115

Vibration-rotation transitions of diacetylene between the first excited states of the ν₆ (CCH symmetric bending) and the ν₈ (CCH antisymmetric bending) vibrations were observed with a Stark modulation microwave spectrometer. The rotational, centrifugal distortion and l-type doubling constants of the two vibrational states were determined as follows with 2.5 σ uncertainties in parentheses.

	35Cl11B32S	35Cl10B32S	37Cl11B32S	35Cl10B32S
$\text{B}{}_0$	2796.7796(7)	2796.8613(14)	2722.9999(6)	2723.2127(17) MHz
$\text{D}{}_0$	344.0(8.0)	327.0(17.0)	321.0(7.0)	328.0(21.0) Hz
$\text{α}{}_2$	?7.4889(7)	?7.8745(15)	?7.2941(15)	?7.6742(17) MHz
$\text{α}{}_3$	3.4620(2)	3.7731(4)	3.4755(2)	3.6354(3) MHz
$\text{q}{}_2$	1.9942(9)	1.9160(7)	1.8954(7)	1.8190(7) MHz
$\text{eQq}\text{(Cl)}$	?42.54(1)	?42.56(2)	?33.53(1)	?33.58(3) MHz
μ	1.45(8)	—	—	— D

     

17.

The ν₁ and 3ν₁ bands of HNCO     

M. Carlotti  G. di Lonardo  G. Galloni  A. Trombetti 《Journal of Molecular Spectroscopy》1976,62(2):192-200

The infrared absorption of HNCO has been measured in the region of the NH stretching fundamental and in that of the second overtone. The results for the excited states are (in cm^?1):

	$\text{B}{}_{\mathrm{v}}\text{(}\text{MHz}\text{)}$	$\text{D}{}_{\mathrm{v}}\text{(}\text{kHz}\text{)}$	$\text{q}{}_{\mathrm{v}}\text{(}\text{MHz}\text{)}$
$\text{ν}{}_6$	4391.3230(84)	0.582(154)	2.4830(32)
$\text{ν}{}_8$	4391.1921(94)	0.594(179)	2.4073(37)

     

18.

Vibration-rotation and deperturbation analysis of A²Π-X²Σ⁺ and B²Σ⁺-X²Σ⁺ systems of the CaI molecule     

David E Reisner  Peter F Bernath  R.W Field 《Journal of Molecular Spectroscopy》1981,89(1):107-124

Doppler-limited laser excitation spectroscopy employing narrow-band fluorescence detection was used to obtain a rotational and vibrational analysis in the (0, 0) and (1, 1) bands of the A²Π-X²Σ⁺ system and the (4, 2) (3, 1), (0, 0), (0, 1), (1, 2), (2, 3), and (3, 4) bands of the B²Σ⁺-X²Σ⁺ system of CaI. The A and B states are deperturbed to obtain spectroscopic constants and Franck-Condon factors. Deperturbation was necessary because of the small separation of the A and B states relative to the A ～ B interaction strength and the A²Π spin-orbit splitting. The main deperturbed constants (in cm^?1) are

Band	$\text{ν}{}_0$	$\text{A-}\text{B}$	B	C
$\text{ν}{}_1$	3533.1	27.0	—	—
$\text{3ν}{}_1$	10145.79	22.6713	0.368426	0.361722

     

19.

The electronic spectrum of PrO. Energy linkages,rotational analysis,and hyperfine structure for systems XVII and XXI     

Michael Dulick  Robert W. Field  J.Cl. Beaufils  J. Schamps 《Journal of Molecular Spectroscopy》1981,87(1):278-288

Doppler-limited laser excitation spectra for four bands of PrO have been recorded: System XvII 0-0, System XXI 0-0 and 0–1, and the 0-0 intercombination between the upper and lower states, respectively, of Systems XVII and XXI. First lines in R and P branches prove that Systems XVII and XXI are, respectively, $\text{Ω}\text{′ = 4.5 ?}\text{Ω}\text{″ = 3.5}$ and $\text{Ω}\text{′ =}\text{Ω}\text{″ = 4.5}$. Hyperfine components are well resolved for all four excitation bands. Rotational and hyperfine constants are determined by least-squares fits of data from all four bands together. In addition, fluorescence spectra, recorded from various J′, v′ = 0 levels of the upper states of Systems XVII and XXI, reveal five new low-lying states. Principal constants (in cm^?1) for nine $\text{Ω-states}$ follow (1σ uncertainty in parentheses):

	$\text{X}{}^2\text{Σ}{}^{\mathrm{+}}$	$\text{A}{}^2\text{Π}$	$\text{B}{}^2\text{Σ}{}^{\mathrm{+}}$
$\text{T}{}_{\mathrm{e}}$	0	15 624.67(5)	15 700.52(12)
$\text{ω}{}_{\mathrm{e}}$	238.7496(33)	241.19(7)	242.63(17)
$\text{ω}{}_{\mathrm{e}}\text{χ}{}_{\mathrm{e}}$	0.62789(64)	0.53(5) (Pekeris)	1.17(12) (Pekeris)
$\text{B}{}_{\mathrm{e}}$	0.0693254(84)	0.070460(14)	0.071572(22)
$\text{α}{}_{\mathrm{e}}\text{× 10}{}^4$	2.640(35)	2.15(10)	3.95(2)
$\text{A}{}_{\mathrm{e}}$	—	45.8968(52)	—
$\text{R}{}_{\mathrm{e}}\text{(}\text{A}\text{?}\text{)}$	2.8286(2)	2.8057(3)	2.7839(4)

     

20.

High-resolution laser excitation spectroscopy: Analysis of the B2Σ+-X2Σ+ system of CaCl     

Peter J. Domaille  Timothy C. Steimle  Ning Bew Wong  David O. Harris 《Journal of Molecular Spectroscopy》1977,65(3):354-365

Single-mode cw dye laser excitation spectra of the (0, 0), (1, 1), and (2, 2) bands of the B²Σ⁺-X²Σ⁺ system of CaCl have been observed and assigned. Some 300 independent photo-luminescence spectra have been used in making the rotational assignment and demonstrate the power of the technique of line-by-line analysis in unraveling complex spectra. Spectroscopic constants (cm^?1) obtained from a weighted least squares fit of the data are given below. Numbers in parentheses refer to 95% confidence limits in the last digit.

State	$\text{T}{}_{\mathrm{v}}$	$\text{B}{}_{\mathrm{v}}$	$\text{d}\text{(hfs)}$
$\text{Ω′ = 4.5 (System XXI)}$	18 882.388 (2)	0.353001 (18)	0.12403 (71)
$\text{Ω′ = 4.5 (System XVII)}$	16 594.075 (1)	0.353736 (20)	0.12977 (67)
$\text{Ω}\text{″ = 3.5}$	3 887.15 (16)	0.35751 (28)	—
$\text{Ω}\text{″ = 3.5}$	2 931.66 (15)	0.35712 (21)	—
$\text{Ω}\text{″ = 4.5}$	2 155.16 (30)	0.36264 (67)	—
$\text{Ω}\text{″ = 5.5}$	2 099.16 (31)	0.35079 (71)	—
$\text{Ω}\text{″ = 3.5}$	2 064.34 (13)	0.35654 (20)	—
$\text{Ω″ = 4.5 (System XXI)}$	217.383 (1)	0.362134 (20)	0.27744 (66)
$\text{Ω″ = 3.5 (System XVII)}$	0.0	0.360948 (16)	?0.00809 (85)

     

	$\text{X}{}^2\text{Σ}{}^{\mathrm{+}}$	$\text{B}{}^2\text{Σ}{}^{\mathrm{+}}$
$\text{T}{}_{\mathrm{e}}$	0	16856.69(2)
$\text{ω}{}_{\mathrm{e}}$	369.8(10)	366.8(10)
$\text{ω}{}_{\mathrm{e}}\text{x}{}_{\mathrm{e}}$	1.13(20)	1.28(20)
$\text{B}{}_{\mathrm{e}}$	0.15200(54)	0.15448(54)
$\text{α}{}_{\mathrm{e}}$	0.00063(34)	0.00073(35)
$\text{D}{}_{\mathrm{e}}$	1.027(16) × 10?7	1.097(17) × 10?7
$\text{γ}{}_{\mathrm{e}}$ (spin-rotation)	+0.003	?0.0630(16)

Stark spectroscopy with the CO laser: The ν2 fundamentals of H2CO and D2CO

The ν₂ (CO stretching) vibration-rotation bands of H₂CO and D₂CO near 5.8 μm have been studied using the technique of laser Stark spectroscopy. The following vibrational and rotational constants have been determined:

The absorption spectrum of the Ag2 molecule

The high dispersion absorption spectrum of the Ag₂ molecule has been photographed in the ～5300–1500-Å region. Observations include the previously reported A ← X, B ← X, C ← X, D ← X, and E ← X transitions and a new H ← X transition which occurs in the vacuum ultraviolet. Extensive spectral blending precluded detailed rotational analyses, but the band structures are consistent with $\text{ΔΩ}\text{= 0}$ and $\text{ΔΩ}\text{≥1}$ for D-X and C-X, respectively. The H state is perturbed and probably predissociated. The following molecular constants (in cm^?1) were obtained from fitting bandhead data to the usual expressions:

The rotation-inversion spectrum of 15NH3

The rotation-inversion spectrum of ¹⁵NH₃ has been recorded between 38 and 280 cm^?1 with a resolution of about 0.03 cm^?1. By combining the present results with the inversion frequencies obtained by microwave spectroscopy, the following main rotational and centrifugal distortion constants were derived (in cm^?1):

The ν3 fundamental band of HDCO

The ν₃ fundamental band (CO stretch) of HDCO at 1724 cm^?1 has been studied using both conventional infrared absorption and CO laser Stark spectroscopy. In addition to the excited-state (v₃ = 1) rotational constants, improved constants for the ground state of HDCO have been obtained by combining previous microwave data with some infrared combination differences. The following constants were determined:

Laser Stark spectroscopy in the 10 μm region: The ν3 bands of CH3F

Laser Stark spectroscopy of the ν₃ band of CH₃F has been carried out using coincidences with the 9.4 μm band CO₂ laser lines. About 350 Stark resonances were measured for the ν₃ fundamental bands of ¹²CH₃F and ¹³CH₃F. About 30 of them were measured by using a Stark-Lamb dip technique to increase the resolution and the accuracy of the data. These Stark resonances, together with the recent results of infrared-microwave two-photon Lamb dip measurements, were analyzed to give the following vibration-rotation parameters and the dipole moments in the ν₃ state,

Laser Stark spectroscopy of formaldehyde-d2: The Coriolis coupled ν4 and ν6 fundamentals

Using CO₂ and N₂O lasers, we have measured and assigned nineteen ν₄ and nine ν₆ rotation-vibration resonances of the type ΔM = 0 and M = J. These transitions were combined with the zero-field pure rotational spectra in order to determine the two fundamental vibrational frequencies, the rotational constants of both excited states, the Coriolis coupling constant, and the dipole moments of each of the three states. The ground-state rotational constants and centrifugal distortion constants were taken from a microwave study and the centrifugal distortion constants of the excited states were assumed equal to those of the ground state. The following results were obtained (standard deviations in parentheses):

High-resolution Fourier transform spectroscopy of the ν2 and ν3 fundamentals of nitrosyl fluoride,FNO

The ν₂ and ν₃ fundamentals of FNO have been recorded with a Fourier transform spectrophotometer at an apodized resolution of approximately 0.004 cm^?1. The Fourier infrared data have been analyzed together with previous microwave data to yield improved molecular parameters for the (000) and (010) vibrational states and the first set of constants for the (001) state. The main results (in cm^?1) are

Absorption spectrum of BS2 at 4°K

BS₂, trapped in neon matrices at 4°K, exhibits extensive progressions in the A²Π_u ← X²Π_g and $\text{B}{}^2\text{Σ}{}_{\mathrm{u}}{}^{\mathrm{+}}\text{← X}{}^2\text{Π}{}_{\mathrm{g}}$ systems. From these transitions, those observed in the infrared, and a reinterpretation of gas-phase data, the following molecular constants (in solid neon) are obtained for linear symmetric ¹¹BS₂ (in cm^?1):

The 10.4 μm CO2 laser Stark spectra of the ν4 and the ν9 bands of 1,1 difluoroethylene

The ν₄ and the ν₉ bands of CF₂CH₂ have been studied using coincidences with the 10.4 μm band of the CO₂ laser and the 10.9 μm band of the N₂O laser. These resonances have been analyzed, together with recent microwave results, to give the following vibration-rotation parameters and dipole moments in the ν₄ and ν₉ states

Acoustical measurement of solid state non-linearity: Application to CsCdF3 and KZnF3

Combination of the results of two sets of measurements on the same crystalline samples of CsCdF₃ and KZnF₃ has made possible the evaluation of the third-order elastic (TOE) constants of these two fluoroperovskites. In the first technique the hydrostatic pressure dependence of the velocity of ultrasonic waves of different propagation and polarization directions has been measured to determine three linear combinations of TOE constants. In the second technique the fundamental and the second harmonic amplitudes of an initially sinusoidal longitudinal ultrasonic wave of finite amplitude propagating along the principal directions have been measured to determine three other linear combinations. Combination of the two sets of data leads to the following room temperature values of the TOE constants (in units of 10¹² dynes/cm²):

The A1Π-X1Σ band system of CD+: Spectroscopic constants and isotope shifts

Six bands of the A¹Π-X¹Σ system of CD⁺ in the region 3800–4800 Å have been recorded in emission using an aluminum hollow-cathode discharge in the HeC₂H₂ mixture. From the vibrational and rotational analysis of the observed bands, the following constants (cm^?1) are obtained:

CO2 laser Stark spectroscopy of the Coriolis-coupled ν2 and ν5 bands of CD3Br

The ν₂ (CD₃ symmetrical deformation) and ν₅ (CD₃ degenerate deformation) fundamental bands of CD₃Br were studied by 9.4- and 10.4-μm CO₂ laser Stark spectroscopy. Stark resonances originating from 28 and 53 rovibrational transitions of the ν₂ and ν₅ bands, respectively, were assigned for each of the isotopic species, CD₃⁷⁹Br and CD₃⁸¹Br. These two bands were simultaneously analyzed with explicit inclusion of the ν₂-ν₅ Coriolis interaction, yielding precise molecular constants in the ν₂ and ν₅ excited states as well as the Coriolis coupling constant. The molecular constants obtained are consistent between the two isotopic species and are in good agreement with the results of high-resolution infrared studies. The band origins and dipole moments are

Fluorescence of the bromine molecules affer selective excitation by a single-mode krypton-lon laser

Optical-optical double-resonance (OODR) spectra of CaF are recorded, with reduced Doppler broadening, using two cw, single-mode dye lasers. Molecular constants for E²Σ⁺ and $\text{E′}{}^2\text{Π}$ are obtained from rotational analysis of the 0-0 and 1-0 E²Σ⁺-A²Π bands and the 0-0 $\text{E′}{}^2\text{Π}\text{-A}{}^2\text{Π}$ band, supplemented by fragmentary observations on the E′-A 0-1 and 1-1 bands:

The microwave spectrum of the transient molecule chloro(sulphido)boron,ClBS: Substitution structure,dipole moment,quadrupole moment,and vibration-rotation analysis

The rotational spectrum of the new reactive triatomic molecule chloro(sulphido)boron, ClBS, produced by the high-temperature reaction of gaseous dichloro disulphide, Cl₂S₂, and crystalline boron at ca. 1000°C was studied by microwave spectroscopy between 26.5 and 40 GHz. Ground state rotational constants have been obtained for 11 of the 12 isotopic variants involving ³⁵Cl, ³⁷Cl, ¹¹B, ¹⁰B, ³²S, ³³S, and ³⁴S; the isotopic shifts for the ground state lines of ³⁵Cl¹⁰B³⁴S from those of ³⁵Cl¹¹B³⁴S are too small and they are overlapped by the ¹¹B species. The abundance of rotational constant data has allowed a detailed comparison of various structure determination procedures to be made. The substitution method yields an extremely consistent ClS distance of 3.28715 ± 0.00005 Å. Application of the first moment condition allows the B atom, which lies close to the center of mass, to be quite accurately located. The resulting bond lengths are $\text{r(}\text{ClB}\text{) = 1.681 ± 0.001}\text{A}\text{?}$ and $\text{r(}\text{BS}\text{) = 1.606 ± 0.001}\text{A}\text{?}$. The more important derived spectroscopic parameters are:

Microwave spectroscopy of the ν8-ν6 band of diacetylene

Vibration-rotation transitions of diacetylene between the first excited states of the ν₆ (CCH symmetric bending) and the ν₈ (CCH antisymmetric bending) vibrations were observed with a Stark modulation microwave spectrometer. The rotational, centrifugal distortion and l-type doubling constants of the two vibrational states were determined as follows with 2.5 σ uncertainties in parentheses.

The ν1 and 3ν1 bands of HNCO

The infrared absorption of HNCO has been measured in the region of the NH stretching fundamental and in that of the second overtone. The results for the excited states are (in cm^?1):

Vibration-rotation and deperturbation analysis of A2Π-X2Σ+ and B2Σ+-X2Σ+ systems of the CaI molecule

Doppler-limited laser excitation spectroscopy employing narrow-band fluorescence detection was used to obtain a rotational and vibrational analysis in the (0, 0) and (1, 1) bands of the A²Π-X²Σ⁺ system and the (4, 2) (3, 1), (0, 0), (0, 1), (1, 2), (2, 3), and (3, 4) bands of the B²Σ⁺-X²Σ⁺ system of CaI. The A and B states are deperturbed to obtain spectroscopic constants and Franck-Condon factors. Deperturbation was necessary because of the small separation of the A and B states relative to the A ～ B interaction strength and the A²Π spin-orbit splitting. The main deperturbed constants (in cm^?1) are

The electronic spectrum of PrO. Energy linkages,rotational analysis,and hyperfine structure for systems XVII and XXI

Doppler-limited laser excitation spectra for four bands of PrO have been recorded: System XvII 0-0, System XXI 0-0 and 0–1, and the 0-0 intercombination between the upper and lower states, respectively, of Systems XVII and XXI. First lines in R and P branches prove that Systems XVII and XXI are, respectively, $\text{Ω}\text{′ = 4.5 ?}\text{Ω}\text{″ = 3.5}$ and $\text{Ω}\text{′ =}\text{Ω}\text{″ = 4.5}$. Hyperfine components are well resolved for all four excitation bands. Rotational and hyperfine constants are determined by least-squares fits of data from all four bands together. In addition, fluorescence spectra, recorded from various J′, v′ = 0 levels of the upper states of Systems XVII and XXI, reveal five new low-lying states. Principal constants (in cm^?1) for nine $\text{Ω-states}$ follow (1σ uncertainty in parentheses):

High-resolution laser excitation spectroscopy: Analysis of the B2Σ+-X2Σ+ system of CaCl

Single-mode cw dye laser excitation spectra of the (0, 0), (1, 1), and (2, 2) bands of the B²Σ⁺-X²Σ⁺ system of CaCl have been observed and assigned. Some 300 independent photo-luminescence spectra have been used in making the rotational assignment and demonstrate the power of the technique of line-by-line analysis in unraveling complex spectra. Spectroscopic constants (cm^?1) obtained from a weighted least squares fit of the data are given below. Numbers in parentheses refer to 95% confidence limits in the last digit.