ABSTRACT
From a comparison with the spectrum of NiF, a low-lying (2)Sigma(+) state is expected to lie in the first 2000 cm(-1) above the ground X(2)Pi(3/2) state of NiCl. The identification of this (2)Sigma(+) (v = 0) state (at 1768 cm(-1)) has been carried out through the analysis of two electronic transitions (2)Pi(3/2)-(2)Sigma(+) (22 720 cm(-1)) and (2)Pi(1/2)-(2)Sigma(+) (23 210 cm(-1)) recorded by high-resolution Fourier transform spectroscopy. Dispersed fluorescence spectroscopy allowed these transitions to be located on an absolute energy-level diagram that includes the previously studied electronic states. Copyright 2000 Academic Press.
ABSTRACT
The A'(1)Pi-X(1)Sigma(+) near-infrared system of CaO was observed for the first time at high resolution using a Fourier transform spectrometer. The A'(1)Pi-X(1)Sigma(+) chemiluminescence was excited in a Ca + N(2)O flame produced in a Broida-type oven. More than 3000 rotational lines, classified into 19 bands involving the A'(1)Pi 0 /= 2) levels with the nearby b(3)Sigma(+) (v-2) levels has been detected. An extended set of A'(1)Pi (v = 0-3) data has been obtained which is suitable for use in a future multistate deperturbation analysis of the a(3)Pi approximately A'(1)Pi approximately b(3)Sigma(+) approximately A(1)Sigma(+) complex of excited states. The new near-infrared spectra of the A'(1)Pi-X(1)Sigma(+) transition of CaO also permits the first direct high-resolution linkage between the orange and green systems and the near-infrared bands. Copyright 2000 Academic Press.
ABSTRACT
The infrared vibration-rotation bands of SeH have been measured in the X(2)Pi ground state using a Fourier transform spectrometer. The bands were observed in a microwave discharge of a mixture of H(2) and Se in the presence of He. The rotational structure of the 1-0, 2-1, 3-2 bands of the X(2)Pi(3/2) spin component and the 1-0 band of X(2)Pi(1/2) spin component has been observed in the 1800-2600 cm(-1) region. The principal ground state molecular constants obtained are omega(e) = 2421.7153(234) cm(-1), omega(e)x(e) = 44.6012(110) cm(-1), omega(e)y(e) = 0.20697(236) cm(-1), B(e) = 7.899187(696) cm(-1), alpha(e) = 0.220749(399) cm(-1), and r(e) = 1.464319(64) Å. This work is the first determination of the equilibrium molecular constants of the X(2)Pi state of SeH. Copyright 2000 Academic Press.
ABSTRACT
The A(1)Sigma(+)-X(1)Sigma(+) chemiluminescence spectrum of SrO was observed using a Fourier transform spectrometer. SrO was produced in a Broida-type oven from the Sr + N(2)O reaction. A total of 75 bands from (88)SrO, (87)SrO, and (86)SrO were measured in the range of 7600-13 600 cm(-1) at a resolution of 0.04 cm(-1). The vibrational levels of the ground state were observed up to v" = 12 and over 10 000 rovibrational lines with J as high as 153 were analyzed at a precision of about 0.005 cm(-1). Significantly improved spectral constants for the ground state were obtained by representing the perturbed excited state by term values and by adding the known microwave data and infrared data to our fit. Strong perturbations were observed in the upper A state. The vibrational levels of the A(1)Sigma(+) state were measured up to v' = 8 and some new perturbations are reported. Copyright 2000 Academic Press.
ABSTRACT
The A(2)Pi(r)-X(2)Sigma(+) emission spectrum of the magnesium monobromide radical, MgBr, has been recorded with a Fourier transform spectrometer modified to record double-sided interferograms. The emission spectra of the Deltav = -2, -1, 0, +1 bands were generated in a microwave discharge of a mixture of argon and vaporized MgBr(2). The Deltav = 0 and -1 bands were rotationally resolved, but the F(2) spin component (A(2)Pi(3/2)) in the (1, 1), (1, 2) and vibrational bands with v' > 1 were missing in our spectra because of a strong predissociation in the A state. The molecular constants in both electronic states were determined for the two bromine isotopomers. The r(0) bond length in the A state is about 2.327 Å, which is about 0.02 Å shorter than in the ground state. Franck-Condon factors were calculated from the Rydberg-Klein-Rees potentials, and they reproduce the observed relative intensities of the bandheads. An upper limit for the dissociation energy (D(0)(0)) was obtained as 26 268.4 cm(-1), based on the absence of the energy level with v = 1, A(2)Pi(3/2), J = 1.5 in our spectrum. Copyright 2000 Academic Press.
ABSTRACT
The high-resolution spectrum of NbN has been investigated in emission in the 3000-15 000 cm(-1) region using a Fourier transform spectrometer. The bands were excited in a microwave discharge through a mixture of NbCl(5) vapor, approximately 5 mTorr of N(2), and 3 Torr of He. Numerous bands observed in the near-infrared region have been classified into the following transitions: f(1)Phi-c(1)Gamma, e(1)Pi-a(1)Delta, C(3)Pi(0+)-A(3)Sigma(-)(1), C(3)Pi(0-)-A(3)Sigma(-)(1), C(3)Pi(1)-a(1)Delta, C(3)Pi(1)-A(3)Sigma(-)(0), d(1)Sigma(+)-A(3)Sigma(-)(0), and d(1)Sigma(+)-b(1)Sigma(+). These observations are consistent with the energy level diagram provided by laser excitation and emission spectroscopy [Y. Azuma, G. Huang, M. P. J. Lyne, A. J. Merer, and V. I. Srdanov, J. Chem. Phys. 100, 4138-4155 (1993)]. The missing d(1)Sigma(+) state has been observed for the first time and its spectroscopic parameters are consistent with the theoretical predictions of S. R. Langhoff and W. Bauschlicher, Jr. [J. Mol. Spectrosc. 143, 169-179 (1990)]. Rotational analysis of a number of bands has been obtained and improved spectroscopic parameters have been extracted for the low-lying electronic states. The observation of several vibrational bands with v = 1 has enabled us to determine the vibrational intervals and equilibrium bond lengths for the A(3)Sigma(-)(0), a(1)Delta, b(1)Sigma(+), d(1)Sigma(+), and C(3)Pi(1) states. Copyright 2000 Academic Press.
ABSTRACT
The laser-induced fluorescence (LIF) spectrum of the B(3)Pi(0(+))(u)-X(1)Sigma(+)(g) system of Br(2) was recorded by Fourier transform spectroscopy (FTS). The LIF spectra were obtained by using continuous-wave dye laser excitation in the spectral region 16 800-18 000 cm(-1). About 1800 rotationally resolved lines were recorded in 96 fluorescence progressions, originating from the 10
ABSTRACT
The 0(0)(0) bands of the Ã(2)B(2)-&Xtilde;(2)A(1) and &Btilde;(2)B(1)-&Xtilde;(2)A(1) systems of SrNH(2) were observed at Doppler-limited resolution using a Broida oven source and laser-induced fluorescence detection. A full rotational analysis of both transitions was performed including K(a) levels up to 5 and J levels up to 55. The &Btilde;(2)B(1) state was found to be extensively perturbed and only some of the subbands could be analyzed. The Ã(2)B(2) and &Btilde;(2)B(1) states undergo a strong Coriolis-type interaction which results in extremely large spin-rotation splittings in both states, effectively splitting all levels with K(a)(') not equal 0 into two well-separated spin components. Copyright 2000 Academic Press.
ABSTRACT
The emission spectrum of IrN was recorded in the near infrared using a Fourier transform spectrometer. The IrN molecules were excited in an Ir hollow cathode lamp operated with a mixture of Ne and a trace of N(2). Numerous IrN bands observed in the 7500-9200 cm(-1) region were assigned to a new a(3)Pi-X(1)Sigma(+) electronic transition with the 0-0 bands of the a(3)Pi(0)-X(1)Sigma(+) and a(3)Pi(1)-X(1)Sigma(+) subbands near 9175 and 8841 cm(-1), respectively. A rotational analysis of several bands of the 0-0 and 0-1 sequences was obtained and molecular constants were extracted. The effective Hund's case (a) constants for the new a(3)Pi state are: T(00) = 8840.31747(88) cm(-1), A(0) = -340.53329(93) cm(-1), DeltaG(1/2) = 984.3629(23) cm(-1), B(e) = 0.4699116(27) cm(-1), alpha(e) = 0.0030058(50) cm(-1), and r(e)= 1.6576432(47) Å. The spectroscopic properties of the ground state and several low-lying electronic states of IrN were also predicted by ab initio calculations. These calculations are consistent with our assignment of the a(3)Pi-X(1)Sigma(+) transition and also support our previous assignments of the A' (1)Pi and A(1)Pi electronic states [R. S. Ram and P. F. Bernath, J. Mol. Spectrosc. 193, 363 (1999)]. The excited a(3)Pi state of IrN has an 1varsigma(2)2varsigma(2)1pi(4)3varsigma(1)1delta(4)2pi(1) electron configuration and the configurations of the other low-lying electronic states are also discussed. Copyright 1999 Academic Press.
ABSTRACT
The emission spectrum of ZrCl has been observed in the 1800-12 000 cm(-1) region using a Fourier transform spectrometer. The molecules were excited in a microwave discharge of a mixture of helium and a trace of ZrCl(4) vapor. In addition to the C(4)Delta-X(4)Phi transition reported previously, numerous new bands observed in the near infrared have been classified into two electronic transitions, [7.3](2)Delta-a(2)Phi and [9.4](2)Phi-a(2)Phi. Five new bands observed in the 6700-7400 cm(-1) region have been assigned as (2)Delta(3/2)-(2)Phi(5/2) and (2)Delta(5/2)-(2)Phi(7/2) subbands of a new electronic transition, [7.3](2)Delta-a(2)Phi. The two subbands of the [9.4](2)Phi-a(2)Phi transition were previously observed by G. Phillips, S. P. Davis, and D. C. Galehouse [Astrophys. J. Suppl. 43, 417-434 (1980)], who tentatively labeled them as (2)Pi(1/2)-(2)Pi(1/2) and (2)Pi(3/2)-(2)Pi(3/2) subbands. A number of new bands involving higher vibrational levels have been identified for these two subbands. A rotational analysis of a number of bands of both transitions has been obtained and spectroscopic constants have been determined. Global perturbations have been observed in both spin components of the a(2)Phi state. The assignment of the observed electronic states has been discussed in light of recent theoretical calculations. Copyright 1999 Academic Press.
ABSTRACT
High-resolution emission spectra of TiCl have been recorded in the 10 000-18 000 cm-1 region using a Fourier transform spectrometer. The molecules were excited in a microwave discharge through a flowing mixture of TiCl4 and helium. TiCl bands observed in the 11 000-13 500 cm-1 region have been assigned to a new [12.8]2Phi-a2Phi electronic transition with the 0-0 bands of 2Phi5/2-2Phi5/2 and 2Phi7/2-2Phi7/2 subbands at 12 733.7 and 12 791.5 cm-1, respectively. A rotational analysis of several bands has been obtained, and spectroscopic constants have been extracted. This assignment is supported by the available theoretical calculations and is also consistent with the near infrared measurements of a doublet-doublet transition of ZrCl [J. G. Phillips, S. P. Davis, and D. C. Galehouse, Astrophys. J. Suppl. Ser. 43, 417-434) (1980)]. Copyright 1999 Academic Press.
ABSTRACT
Emission spectra have been recorded for hot water at temperatures up to 1550 degreesC. Separate spectra have been recorded in the 800-1900 and 1800-2500 cm-1 range. Assignments are made using a linelist generated from high accuracy, variational nuclear motion calculations, and energy differences. The spectra contain many hot bending transitions of the form (0n0)-(0n-10), where states up to n = 6 have been assigned. Detailed analysis shows that the spectra contain lines from 34 separate vibrational bands including other hot bending transitions and the difference bands (030)-(100), (110)-(020), (011)-(020), (100)-(010), (040)-(110), (040)-(011), (120)-(030), (012)-(030), (011)-(100), (110)-(001), and (101)-(110), all of which have not been observed previously. From a total of 8959 lines recorded, 6810 have been assigned; 4556 of these lines are new. These spectra represent the first detection of the (060) vibrational band, for which a band origin of 8870.54 +/- 0.05 cm-1 is determined. The (050) band origin is confirmed as 7542.40 +/- 0.03 cm-1. The assignments extend the range of J and Ka values observed for the bending states, particularly for (050) and (060), where 63 and 27 different rotational levels, respectively, have now been observed; 53 frequencies given in HITRAN are corrected. Copyright 1999 Academic Press.
ABSTRACT
The emission spectrum of IrN has been investigated in the 10 000-20 000 cm-1 region at 0.02 cm-1 resolution using a Fourier transform spectrometer. The bands were excited in an Ir hollow cathode lamp operated with a mixture of 2 Torr of Ne and a trace of N2. Numerous bands have been classified into two transitions labeled as A1Pi-X1Sigma+ and A' 1Pi-X1Sigma+ by analogy with the isoelectronic PtC molecule. Ten bands involving vibrational levels up to Kv = 4 in the ground and excited states have been identified in the A1Pi-X1Sigma+ transition. This electronic transition has been previously observed by [A. J. Marr, M. E. Flores, and T. C. Steimle, J. Chem. Phys. 104, 8183-8196 (1996)]. To lower wavenumbers, five additional bands with R heads near 12 021, 12 816, 13 135, 14 136, and 15 125 cm-1 have been assigned as the 0-1, 3-3, 0-0, 1-0, and 2-0 bands, respectively, of the new A' 1Pi-X1Sigma+ transition. A rotational analysis of these bands has been carried out and equilibrium constants for the ground and excited states have been extracted. The Kv = 2 and 3 vibrational levels of the A' 1Pi state interact with the Kv = 0 and 1 levels of the A1Pi state and cause global perturbations in the bands. The ground state equilibrium constants for 193IrN are: omegae = 1126.176360(61) cm-1, omegaexe = 6.289697(32) cm-1, Be = 0.5001033(20) cm-1, alphae = 0.0032006(20) cm-1, and re = 1.6068276(32) Å. Copyright 1999 Academic Press.
ABSTRACT
Extensive new high-temperature, high-resolution FTIR emission spectroscopy measurements for the five common isotopomers of GeO are combined with previous diode laser and microwave measurements in combined isotopomer analyses. New Dunham expansion parameters and an accurate analytical potential energy function are determined for the ground X1Sigma+ state. Copyright 1999 Academic Press.
ABSTRACT
The A2Pi-X2Sigma+ Deltav = 0 sequence of BeD was observed in the 19 500-20 800 cm-1 spectral region using a Fourier transform spectrometer. The emission spectrum was excited in a Be hollow cathode discharge lamp with a He/D2 gas mixture. The observed lines were assigned to the 0-0 to 6-6 bands. The Deltav = -1 sequence was too weak to be seen in our Fourier transform spectra. We therefore used a previously recorded but unpublished arc emission spectrum to identify the 0-1 to 5-6 Deltav = -1 bands. Consequently, all of the diagonal bands could be linked together and the vibrational intervals determined. The Deltav = 0 and Deltav = -1 data were fitted together in a global fit and effective constants derived. Using the information available from the study of the C2Sigma+-X2Sigma+ system [R. Colin, C. Drèze, and M. Steinhauer, Can. J. Phys. 61, 641 (1983)], the v = 8-12 vibrational levels of the ground state were added in a Dunham fit. A set of Dunham Y constants was determined for the X2Sigma+ state along with traditional equilibrium parameters for the A2Pi excited state. The equilibrium bond lengths were found to be 1.341742(5) Å for the ground state and 1.33309(4) Å for the excited state. A reanalysis of the previously published A2Pi-X2Sigma+ 0-0 to 3-3 Deltav = 0 bands of BeT [D. De Greef and R. Colin, J. Mol. Spectrosc. 53, 455-465 (1974)] was also performed. Copyright 1998 Academic Press.
ABSTRACT
The emission spectra of the A2Delta-X2Pi transition of SiH and SiD have been observed at high resolution using a Fourier transform spectrometer. The molecules were excited in a Si hollow cathode lamp by passing a discharge through a mixture of Ne and a trace of H2 or D2. The present data, combined with the previous infrared vibration-rotation measurements, have been used to determine improved molecular constants for the ground and excited states of SiH and SiD. Copyright 1998 Academic Press.
ABSTRACT
The emission spectrum of TaO, excited in a tantalum hollow cathode lamp, has been observed at high resolution using a Fourier transform spectrometer. In addition to previously known transitions, a number of new bands have been identified and assigned as belonging to two new electronic transitions: H2Pi1/2-X2Delta3/2 and K2Phi5/2-X2Delta3/2. A rotational analysis ofthe 0-0 and 0-1 bands of the H2Pi1/2-X2Delta3/2 transition and of the 0-1, 1-2, 0-0, 1-0, and 2-1 bands of theK2Phi5/2-X2Delta3/2 transition has been carried out, providing the following equilibrium constants for the ground X2Delta3/2 state:omegae = 1028.9060(15) cm-1, omegaexe = 3.58928(66) cm-1, Be = 0.40289737(139) cm-1, alphae = 0.00185445(83) cm-1, andre = 1.6873430(29) Å. The principal molecular constants for the H2Pi1/2 state are T00 = 20 634.32758 (40) cm-1,B0 = 0.3766867(31) cm-1, and r0 = 1.7450604(72) Å, while the equilibrium constants for the K2Phi5/2 state areomegae = 905.4549(15) cm-1, omegaexe = 3.67601(64) cm-1, Be = 0.37965102(36) cm-1, alphae = 0.00189370(21) cm-1, andre = 1.7382343(8) Å. Although the H2Pi1/2 and K2Phi5/2 states have been observed previously in matrix isolation experiments, our work on these states is the first in the gas phase. Copyright 1998 Academic Press.
ABSTRACT
The near-infrared emission spectrum of He2, excited in a Be hollow cathode discharge, has been recorded at high resolution using a Fourier transform spectrometer. The c3Sigma+
ABSTRACT
High-resolution Fourier transform spectra of LiH and LiD were recorded in the far-infrared region, 100-360 cm-1, and the mid-infrared regions, 800-1200 cm-1 and 2000-3000 cm-1. A total of 261 pure rotational lines and 678 rovibrational lines were measured for the isotopomers 6LiH(D) and 7LiH(D). Molecular constants for the X1Sigma+ ground state in the form of mass-dependent Dunham Yij's and mass-independent Dunham Uij's were determined from a data set of 1476 lines, consisting of our measured line positions and previously reported microwave, millimeter-wave, and infrared lines. An effective internuclear potential for the ground electronic state where the Born-Oppenheimer part is modeled as a parameterized modified-Morse function was also determined from a fit of the data. Copyright 1998 Academic Press.
