FT-spectroscopy of the 12C18O rare isotopologue and deperturbation analysis of the A1Π(v = 3) level

Research on 12C18O was carried out using two complementary Fourier-transform methods: (1) vacuum-ultraviolet absorption spectroscopy, with an accuracy ca. 0.03 cm-1 on the DESIRS beamline (SOLEIL synchrotron) and (2) visible emission spectroscopy with an accuracy of about 0.005-0.007 cm-1 by means of the Bruker IFS 125HR spectrometer (University of Rzeszów). The maximum rotational quantum number of the energy levels involved in the observed spectral lines was Jmax = 54. An effective Hamiltonian and the term-value fitting approach were implemented for the precise analysis of the A1Π(v = 3) level in 12C18O. It was performed by means of the PGOPHER code. The data set consisted of 571 spectral lines belonging to the A1Π-X1Σ+(3, 0), B1Σ+-A1Π(0, 3), C1Σ+-A1Π(0, 3) bands and several lines involving states that perturb the A1Π(v = 3) level as well as to the previously analysed B1Σ+-X1Σ+(0, 0) and C1Σ+-X1Σ+(0, 0) transitions. A significantly extended quantum-mechanical description of the A1Π(v = 3) level in 12C18O was provided. It consists of the 5 new unimolecular interactions of the spin-orbit and rotation-electronic nature, which had not been taken into account previously in the literature. The ro-vibronic term values of the A1Π(v = 3, Jmax = 55), a'3Σ+(v = 13), D1Δ(v = 4) and I1Σ-(v = 5) levels were determined with precision improved by a factor of 10 relative to the previously known values.

Anomalous Intensities in the 2+1 REMPI Spectrum of the E 1Π-X 1Σ+ Transition of CO

We report on one-color experiments near 214 nm involving the photodissociation of jet-cooled OCS to produce high rotational states (40 < J < 80) of CO (X ¹Σ⁺, v = 0, 1) which were then ionized by 2+1 resonance-enhanced multiphoton ionization via the E ¹Π state. The nominally forbidden Q-branch of the two-photon E ¹Π-X ¹Σ⁺ transition is observed with intensity comparable to the allowed R-branch. The bright character of the high- J Q-branch lines can be described quantitatively as intensity borrowing due to mixing of the E ¹Π and C ¹Σ⁺ states, using J-dependent mixing coefficients extrapolated from the observed Λ-doubling in the lower rotational levels of the E state. In addition to the significant enhancement of Q-branch intensities above the values predicted by conventional two-photon line strengths for a ¹Π-¹Σ⁺ transition, the high- J lines of the R- and P-branches appear to be suppressed in intensity by approximately a factor of 3 compared to the unperturbed low- J line strengths, most likely due to perturbations associated with a ¹Σ^- state. The E-state rotational term values for J < 80, v = 0 derived from the present spectra agree within our measurement and calibration uncertainties with the extrapolations based on the molecular constants previously derived from rotational levels with J < 50. The E-X transition is attractive for future application to photodissociation dynamics and rotational polarization measurements of CO photofragments, with convenient access to state-selective probing on multiple rotational branches, which exhibit different sensitivity to fragment alignment.

Experimental studies of the NaCs 12(0+) [71Σ+] state: Spin-orbit and non-adiabatic interactions and quantum interference in the 12(0+) [71Σ+] and 11(0+) [53Π0] emission spectra

We present results from experimental studies of the 11(0⁺) and 12(0⁺) electronic states of the NaCs molecule. An optical-optical double resonance method is used to obtain Doppler-free excitation spectra. Selected data from the 11(0⁺) and 12(0⁺) high-lying electronic states are used to obtain Rydberg-Klein-Rees and Inverse Perturbation Approach potential energy curves. Interactions between these two electronic states are evident in the patterns observed in the bound-bound and bound-free fluorescence spectra. A model, based on two separate interaction mechanisms, is presented to describe how the wavefunctions of the two states mix. The electronic parts of the wavefunctions interact via spin-orbit coupling, while the individual rotation-vibration levels interact via a second mechanism, which is likely to be non-adiabatic coupling. A modified version of the BCONT program was used to simulate resolved fluorescence from both upper states. Parameters of the model that describe the two interaction mechanisms were varied until simulations were able to adequately reproduce experimental spectra.

VIS and VUV spectroscopy of 12C17O and deperturbation analysis of the A1Π, υ = 1–5 levels

The reduced T(J) − B_AJ(J + 1) + D_AJ²(J + 1)² term values for the ¹²C¹⁷O A₁Π (υ = 5) level and for the hypothetical unperturbed crossing rovibronic levels of the perturbers.

New spectroscopic data, spin-orbit functions, and global analysis of data on the AΣu+1 and bΠu3 states of Na2

The lowest electronically excited states of Na2 are of interest as intermediaries in the excitation of higher states and in the development of methods for producing cold molecules. We have compiled previously obtained spectroscopic data on the A 1Sigmau+ and b 3Piu states of Na2 from about 20 sources, both published and unpublished, together with new sub-Doppler linewidth measurements of about 15,000 A<--X transitions using polarization spectroscopy. We also present new ab initio results for the diagonal and off-diagonal spin-orbit functions. The discrete variable representation is used in conjunction with Hund's case a potentials plus spin-orbit effects to model data extending from v=0 to very close to the 3 2S+3 2P12 limit. Empirical estimates of the spin-orbit functions agree well with the ab initio functions for the accessible values of R. The potential function for the A state includes an exchange potential for S+P atoms, with a fitted coefficient somewhat larger than the predicted value. Observed and calculated term values are presented in an auxiliary (EPAPS) file as a database for future studies on Na2.

Quantum defect theory of dipole and vibronic mixing in Rydberg states of CaF

The Rydberg spectra of CaF combine the simplicity of a single electron outside a doubly closed-shell Ca2+F- ion core with the exceptional polarity of the ion core. A global multichannel quantum defect (MQDT) fit to 612 previously assigned levels, 507 from n approximately = 12-18, N=0-14, v+=1, 97 from n approximately = 9-10, N=0-14, v+=2, and 8 from n approximately = 7, N=3-10, v+=3, produces the complete L=0-3 quantum defect matrix mu (with the exception of one element) and 19 of 20 elements of the partial differentialmu/differentialR matrix, as well as the molecular constants of the CaFX 1sigma+ state [omega(e)+=694.58(14), omega(e)x(e+)=2.559(40), B(e+)=0.373 07(16) cm(-1), and the v=0, N=0 to v(+)=0, N(+)=0 ionization energy, 46,996.40(8) cm(-1)]. This experimentally determined mu(R) matrix is unusual in the completeness of its representation of the spectrum of both core-penetrating and nonpenetrating Rydberg series, including both local perturbations and vibrational autoionization rates, as well as all dynamical processes encoded in the spectrum that result from the scattering (at negative energy) of the Rydberg electron off the Ca2+F- ion core. The MQDT theory is presented in a form that clarifies the relationships of the reaction (K) and phase (P) matrices of MQDT to effective Hamiltonian models for local interactions between accidentally near degenerate levels. In particular, a Hund's case (b) like representation of the Hamiltonian is described in which the rovibronic K matrix is diagonalized and the P matrix, which contains information about the v+, N+ eigenstates of the ion, becomes nondiagonal.

Lung cancer histologic type in the surveillance, epidemiology, and end results registry versus independent review

Because few studies have assessed the accuracy of lung cancer histologic diagnoses reported by state cancer registries, we examined whether the Iowa Surveillance, Epidemiology, and End Results Cancer Registry (i.e., the Iowa Cancer Registry)-reported lung cancer histologic diagnoses were reliable. We investigated agreement between lung cancer histologic types reported for 413 patients with lung cancer by the Iowa Cancer Registry and those obtained through an independent review of diagnostic slides. Among lung cancer histologic types, small-cell carcinoma had the highest sensitivity (94.1%, 95% confidence interval [CI] = 85.6% to 98.4%), positive predictive value (94.1%, 95% CI = 85.6% to 98.4%), negative predictive value (98.8%, 95% CI = 96.9% to 99.7%), and highest percent exact agreement (98.0%, 95% CI = 96.6% to 99.4%). The lowest sensitivity (21.9%, 95% CI = 9.3% to 40.0%) and positive predictive value (23.3%, 95% CI = 9.9% to 42.3%) were noted for large-cell carcinoma, probably because other more specific features of adenocarcinoma or squamous carcinoma were absent. Adenocarcinoma had the lowest specificity (84.4%, 95% CI = 79.0% to 88.9%), negative predictive value (85.2%, 95% CI = 79.9% to 89.6%), and percent exact agreement (82.9%, 95% CI = 79.2% to 86.6%). Samples collected by cytologic examination (odds ratio [OR] = 2.4, 95% CI = 1.1 to 5.2) or biopsy examination (OR = 2.2, 95% CI = 1.1 to 4.2) were more likely to be misclassified than samples obtained via resection. Thus, the histologic type obtained by the Iowa Cancer Registry is reasonably reliable, but independent slide review is needed for precise histologic typing of lung cancer.

210Po implanted in glass surfaces by long term exposure to indoor radon

Recent epidemiologic investigations of the relationship between residential radon gas exposure and lung cancer relied on contemporary radon gas measurements to estimate past radon gas exposures. Significant uncertainties in these exposure estimates can arise from year-to-year variation of indoor radon concentrations and subject mobility. Surface implanted 210Po has shown potential for improving retrospective radon gas exposure estimates. However, in previous studies, the ability of implanted 210Po activity to reconstruct cumulative radon gas exposure was not tested because glass was not available from homes with known radon-gas concentration histories. In this study, we tested the validity of the retrospective radon gas reconstruction using implanted 210Po surface activity by measuring glass surfaces from homes whose annual-average radon gas concentrations had been measured almost every year during two decades. Regression analysis showed a higher correlation between measured surface activity and cumulative radon gas exposure in these homes (R2>0.8) than was observed in homes where only contemporary radon gas measurements were available. The regression slope (0.57 ky m(-1)) was consistent with our earlier retrospective results. Surface activity measurements were as reliable for retrospective radon gas exposure reconstruction as yearlong gas measurements. Both methods produced estimates that were within 25% of the long-term average radon gas concentrations in a home. Surface measurements can be used for home screening tests because they can provide rapid, reliable estimates of past radon gas concentrations. Implanted 210Po measurements are also useful in retrospective epidemiologic studies that include participants who may have been exposed to highly variable radon concentrations in previously occupied or structurally modified homes.

Measurement of transition dipole moments in lithium dimers using electromagnetically induced transparency

We have observed electromagnetically induced transparency in a Doppler broadened molecular cascade system using fluorescence detection. We demonstrate that the power-dependent splitting of lines in the upper-level fluorescence excitation spectrum can be used as a new spectroscopic tool for the measurement of molecular transition dipole moment functions.

Lung cancer risk and red meat consumption among Iowa women

OBJECTIVE

Some epidemiologic studies suggest that diets high in total fat, saturated fat, or cholesterol are associated with increased risk of lung cancer. Others suggest that diets high in red meat consumption, particularly well-done red meat, are a lung cancer risk factor. In Iowa, we had the opportunity to investigate concurrently the role of meat intake and macronutrients in lung cancer etiology.

METHODS

A population-based case-control study of both non-smoking and smoking women was conducted in Iowa. A 70-item food frequency questionnaire (FFQ) was completed by 360 cases and 574 frequency-matched controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using logistic regression. Multivariate models included age, education, pack-years of smoking, yellow-green vegetable intake, fruit/fruit juice intake, nutrient density calories, previous non-malignant lung disease, alcohol consumption and body mass index (BMI).

RESULTS

When comparing the fifth (highest) to the first (lowest) quintile of consumption of total fat, saturated fat and cholesterol, we obtained odds ratios of 2.0 (1.3-3.1), 3.0 (1.9-4.7), and 2.0 (1.3-3.0) respectively. However, when red meat was entered into the model along with total fat, saturated fat or cholesterol, the excess risk for the macronutrients disappeared while an odds ratio of 3.3 (1.7-7.6) was obtained for red meat. The odds ratios for red meat consumption were similar among adenocarcinoma cases, OR=3.0 (1.1-7.9) and non-adenocarcinoma cases, OR=3.2 (1.3-8.3) and among life-time nonsmokers and ex-smokers OR=2.8 (1.4-5.4), and current smokers, OR=4.9 (1.1-22.3). Yellow-green vegetables were protective with an odds ratio of 0.4 (0.2-0.7).

CONCLUSIONS

Consumption of red meat, was associated with an increased risk of lung cancer even after controlling for total fat, saturated fat, cholesterol, fruit, yellow-green vegetable consumption and smoking history, while yellow-green vegetables are associated with a decreased risk of lung cancer.

A review of residential radon case-control epidemiologic studies performed in the United States

Lung cancer is the leading cause of cancer death in the United States for both men and women. Although most lung cancer deaths are attributable to tobacco usage, even secondary causes of lung cancer are important because of the magnitude of lung cancer incidence and its poor survival rate. This review summarizes the basic features and major findings from the published U.S. large-scale residential radon case-control studies performed in New Jersey, Iowa, and Missouri (two studies). The methodology from an unpublished study covering Connecticut, Utah, and Southern Idaho is also presented. Overall, the higher categorical risk estimates for these published studies produced a positive association between prolonged radon exposure and lung cancer. Two studies (Missouri-II and Iowa) that incorporated enhanced dose estimates produced the most compelling evidence suggesting an association between prolonged residential radon exposure and lung cancer. The prevailing evidence suggests that the statistically significant findings may be related to improved retrospective radon exposure estimates. The general findings from the U.S. studies, along with extrapolations from radon-exposed underground miners, support the conclusion that after cigarette smoking, prolonged residential radon exposure is the second leading cause of lung cancer in the general population.

The Iowa radon lung cancer study--phase I: Residential radon gas exposure and lung cancer

Exposure to high concentrations of radon (222Rn) progeny produces lung cancer in both underground miners and experimentally-exposed laboratory animals. The goal of the study was to determine whether or not residential radon exposure exhibits a statistically significant association with lung cancer in a state with high residential radon concentrations. A population-based, case-control epidemiologic study was conducted examining the relationship between residential radon gas exposure and lung cancer in Iowa females who occupied their current home for at least 20 years. The study included 413 incident lung cancer cases and 614 age-frequency-matched controls. Participant information was obtained by a mailed-out questionnaire with face-to-face follow-up. Radon dosimetry assessment consisted of five components: (1) on-site residential assessment survey; (2) on-site radon measurements; (3) regional outdoor radon measurements; (4) assessment of subjects' exposure when in another building; and (5) linkage of historic subject mobility with residential, outdoor, and other building radon concentrations. Histologic review was performed for 96% of the cases. Approximately 60% of the basement radon concentrations and 30% of the first floor radon concentrations of study participants' homes exceeded the US Environmental Protection Agency action level of 150 Bq m(-3) (4 pCi l(-1)). Large areas of western Iowa had outdoor radon concentrations comparable to the national average indoor value of 55 Bq m(-3) (1.5 pCi l(-1)). Excess odds of 0.24 (95% CI = -0.05-0.92) and 0.49 (95% CI = 0.03-1.84) per 11 WLM(5-19) were calculated using the continuous radon exposure estimates for all cases and live cases, respectively. Slightly higher excess odds of 0.50 (95% CI = 0.004-1.80) and 0.83 (CI = 0.11-3.34) per 11 WLM(5-19) were noted for the categorical radon exposure estimates for all cases and the live cases. A positive association between cumulative radon gas exposure and lung cancer was demonstrated using both categorical and continuous analyses. The risk estimates obtained in this study indicate that cumulative radon exposure presents an important environmental health hazard.

The dynamics of "stretched molecules": experimental studies of highly vibrationally excited molecules with stimulated emission pumping

We review stimulated emission pumping as used to study molecular dynamics. The review presents unimolecular as well as scattering studies. Topics include intramolecular vibrational redistribution, unimolecular isomerization and dissociation, van der Waals clusters, rotational energy transfer, vibrational energy transfer, gas-surface interactions, atmospheric effects resulting from nonequilibrium vibrational excitation, and vibrational promotion of electron transfer.

Does exposure to residential radon increase the risk of lung cancer?

In assessing the risks of exposure to ionising radiation, it is important to neither overstate nor understate the effects of the hazard. These requirements are often difficult to satisfy, especially since much of our knowledge about the effects of low levels of radiation is subject to rather large uncertainties. Our participants have given their opinions about the risk of lung cancer induction resulting from exposure to radon in residences. Each agrees that exposures to high concentrations of radon are hazardous. However, as with low level exposures to other types of ionising radiation, quantifying relatively small risks is quite difficult. The national and international standards setting bodies have recommended a fairly conservative approach that may overestimate the 'true' magnitude of deleterious effects and their dependence upon exposure, but this is to be expected given the uncertainties in the data and the need to avoid underestimates. A conservative approach can have both positive and negative consequences, and it is also important to neither overstate nor understate these consequences.

The Predissociation of the 1(3)Sigma(-)(g) State of (7)Li(2)

The predissociation of the 1(3)Sigma(-)(g) v >/= 10 levels of (7)Li(2) has been observed by pulsed and continuous-wave perturbation-facilitated optical-optical double-resonance spectroscopy (PFOODR). Our ab initio calculation shows that the inner wall of the 1(3)Sigma(-)(g) potential intersects the 1(3)Pi(g) repulsive potential at internuclear distance R = 2.00 Å. The predissociation is due to a DeltaS = 0, DeltaLambda = +/-1 rotational-electronic interaction with the repulsive 1(3)Pi(g) state. Copyright 2001 Academic Press.

Dissolution of 226Radium from pipe-scale deposits in a public water supply

This study was undertaken to determine if dissolution of 226Radium from pipe-scale deposits contributes to enhanced waterborne 226Radium concentrations at the point of use. Water samples were collected from residential water customers of a small rural Iowa town. Sites were evenly divided between new and old water main connections. Daily samples were collected from the point-of-entry water. Point-of-use 226Radium concentrations ranged from 0.4 to 12.9 pCi L-1 (0.01 to 0.5 Bq L-1). The mean 226 Radium concentration for homes connected to old water mains was significantly higher than the mean 226Radium concentration of homes connected to new water mains, mean(standard deviation) equal 8.3(1.1) and 5.3(0.8) pCi L-1 [0.3(1.1) and 0.2(0.8) Bq L-1], respectively. 226Radium concentrations of the point-of-entry water ranged from 5.0 pCi L-1 to 10.3 pCi L-1 (0.2 Bq L-1 to 0.4 Bq L-1). This study indicates considerable variability of 226Radium exposure from drinking water among residents of the same water supply and has implications for regulatory compliance and exposure assessment in epidemiologic studies.

Bovine teat atresia associated with horn fly (Haematobia irritans irritans (L.))-induced dermatitis

Mammary gland lesions characterized primarily as mammary teat atresia were observed in a Limousin beef cattle herd in eastern Texas. Atresia of multiple teats per mammary gland was reported in first-calf heifers at the time of calving. Pathogens were not identified in eight mammary glands collected at slaughter. Histology of affected glands demonstrated superficial and deep perivascular inflammation and fibrosing dermatitis of teat and mammary gland skin that resulted in formation of the atretic lesions of glandular tissue. Institution of a horn fly (Haematobia irritans irritans (L.)) control program using insecticide-impregnated ear tags was associated with elimination of the problem from the herd.

Residential radon gas exposure and lung cancer: the Iowa Radon Lung Cancer Study

Exposure to high concentrations of radon progeny (radon) produces lung cancer in both underground miners and experimentally exposed laboratory animals. To determine the risk posed by residential radon exposure, the authors performed a population-based, case-control epidemiologic study in Iowa from 1993 to 1997. Subjects were female Iowa residents who had occupied their current home for at least 20 years. A total of 413 lung cancer cases and 614 age-frequency-matched controls were included in the final analysis. Excess odds were calculated per 11 working-level months for exposures that occurred 5-19 years (WLM(5-19)) prior to diagnosis for cases or prior to time of interview for controls. Eleven WLM(5-19) is approximately equal to an average residential radon exposure of 4 pCl/liter (148 Bq/m3) during this period. After adjustment for age, smoking, and education, the authors found excess odds of 0.50 (95% confidence interval: 0.004, 1.81) and 0.83 (95% percent confidence interval: 0.11, 3.34) using categorical radon exposure estimates for all cases and for live cases, respectively. Slightly lower excess odds of 0.24 (95 percent confidence interval: -0.05, 0.92) and 0.49 (95 percent confidence interval: 0.03, 1.84) per 11 WLM(5-19) were noted for continuous radon exposure estimates for all subjects and live subjects only. The observed risk estimates suggest that cumulative ambient radon exposure presents an important environmental health hazard.

Intensity Measurements and Collision-Broadening Coefficients for the Oxygen A Band Measured by Intracavity Laser Absorption Spectroscopy

High-sensitivity, high-resolution intracavity laser absorption spectroscopy (ICLAS) has been used to measure line intensities, nitrogen-broadening coefficients, and self-broadening coefficients in the A band (b(1)Sigma(+)(g) <-- X(3)Sigma(-)(g)) of oxygen. Both linear cavity and ring cavity ICLAS configurations were used for these measurements, and the results were intercompared. The results were compared to values measured using long-path multiple-reflection cells by K. D. Ritter and T. D. Wilkinson [J. Mol. Spectrosc. 121, 1-19 (1987)] and L. Brown and C. Plymate, [J. Mol. Spectrosc. 199, 166-179 (2000)]. New results are included for weakly absorbing transitions, not observed in the earlier measurements, such as high rotational states (up to J = 39), hot-band transitions (v' = 1 <-- v" = 1), and isotopically substituted species ((18)O(2) and (16)O(18)O). Isotopic variants ((16)O(2), (18)O(2), and (16)O(18)O) have similar broadening coefficients for corresponding rotational levels, but the self-broadening coefficients are larger in the hot band (v' = v" = 1) as compared with v' = v" = 0 transitions. An ECS-EP scaling analysis of the v' = v" = 0 self-broadening data accurately represents the available data, with the exception of the N = 0 and N = 1 levels. Copyright 2000 Academic Press.

The 2(3)Delta(g) State of (7)Li(2)

Using pulsed perturbation-facilitated optical-optical double resonance (PFOODR) spectroscopy, the 2(3)Delta(g) state of (7)Li(2) (electronic configuration (varsigma(g)2s) (4ddelta(g)), effective principal quantum number n* = 4.101) has been observed and assigned. Molecular constants and a RKR potential energy curve were obtained. The major molecular constants are Copyright 2000 Academic Press.

Observation of Coriolis Coupling between nu(2) + 4nu(4) and 7nu(4) in Acetylene &Xtilde;(1)Sigma(+)(g) by Stimulated Emission Pumping Spectroscopy

Stimulated emission pumping (SEP) spectroscopy has been used to examine a low energy region (E(vib) approximately 4400 cm(-1)) of &Xtilde;(1)Sigma(+)(g) acetylene at higher resolution than was possible in previous dispersed fluorescence studies. The expected bright state, nu(2) + 4nu(4), is observed to be coupled to the nearly degenerate 7nu(4) state by a Coriolis mechanism. A least-squares analysis yields values for zero-order vibrational energies, rotational constants, and a Coriolis-coupling coefficient that are all consistent with expectations. Calculated relative intensities of SEP transitions, accounting for interference due to axis-switching effects, are also consistent with observations. Implications of the observed Coriolis resonance with regard to global acetylene vibrational dynamics are also discussed. Copyright 2000 Academic Press.

Intercomparison of retrospective radon detectors

We performed both a laboratory and a field intercomparison of two novel glass-based retrospective radon detectors previously used in major radon case-control studies performed in Missouri and Iowa. The new detectors estimate retrospective residential radon exposure from the accumulation of a long-lived radon decay product, (210)Pb, in glass. The detectors use track registration material in direct contact with glass surfaces to measure the alpha-emission of a (210)Pb-decay product, (210)Po. The detector's track density generation rate (tracks per square centimeter per hour) is proportional to the surface alpha-activity. In the absence of other strong sources of alpha-emission in the glass, the implanted surface alpha-activity should be proportional to the accumulated (210)Po, and hence to the cumulative radon gas exposure. The goals of the intercomparison were to a) perform collocated measurements using two different glass-based retrospective radon detectors in a controlled laboratory environment to compare their relative response to implanted polonium in the absence of environmental variation, b) perform collocated measurements using two different retrospective radon progeny detectors in a variety of residential settings to compare their detection of glass-implanted polonium activities, and c) examine the correlation between track density rates and contemporary radon gas concentrations. The laboratory results suggested that the materials and methods used by the studies produced similar track densities in detectors exposed to the same implanted (210)Po activity. The field phase of the intercomparison found excellent agreement between the track density rates for the two types of retrospective detectors. The correlation between the track density rates and direct contemporary radon concentration measurements was relatively high, considering that no adjustments were performed to account for either the residential depositional environment or glass surface type. Preliminary comparisons of the models used to translate track rate densities to average long-term radon concentrations differ between the two studies. Further calibration of the retrospective detectors' models for interpretation of track rate density may allow the pooling of studies that use glass-based retrospective radon detectors to determine historic residential radon exposures.

Analysis and Deperturbation of the A(2)Pi and B(2)Sigma(+) States of CaF

A laser excitation spectrum of the (0, 0) and (1, 1) bands of the CaF A(2)Pi-X(2)Sigma(+) system was recorded. The present set of molecular constants for both A(2)Pi and B(2)Sigma(&plus:) states represents a vast improvement in precision over previously reported values because of the larger number of line position measurements and the use of a more reasonable effective Hamiltonian model which accounts explicitly for the A approximately B interaction via off-diagonal matrix elements. The principal constants (in cm(-1)) are where uncertainties of 1varsigma are given in parentheses. Copyright 1999 Academic Press.

HCP CPH ISOMERIZATION: Caught in the Act

▪ Abstract  In this overview we discuss the vibrational spectrum of phosphaethyne, HCP, in its electronic ground state, as revealed by complementary experimental and theoretical examinations. The main focus is the evolution of specific spectral patterns from the bottom of the potential well up to excitation energies of approximately 25,000 cm−1, where large-amplitude, isomerization-type motion from H–CP to CP–H is prominent. Distinct structural and dynamical changes, caused by an abrupt transformation from essentially HC bonding to mainly PH bonding, set in around 13,000 cm−1. They reflect saddle-node bifurcations in the classical phase space—a phenomenon well known in the nonlinear dynamics literature—and result in characteristic patterns in the spectrum and the quantum-number dependence of the vibrational fine-structure constants. Two polar opposites are employed to elucidate the spectral patterns: the exact solution of the Schrödinger equation, using an accurate potential energy surface and an effective or resonance Hamiltonian (expressed in a harmonic oscillator basis set and block diagonalized into polyads), which is defined by parameters adjusted to fit either the measured or the calculated vibrational energies. The combination of both approaches—together with classical mechanics and semiclassical analyses—provides a detailed spectroscopic picture of the breaking of one bond and the formation of a new one.

Rotational Pattern Difference in Resolved Fluorescence Spectra with Different Detection Schemes

The relative intensities of rotational lines in resolved fluorescence spectra are dependent on the detection direction and the choice of the detection scheme when a grating monochromator is used. These differences arise from the spatially anisotropic distribution of the fluorescence, the rotational branch dependence of the fluorescence polarization, and the polarization dependence of the monochromator grating efficiency. Both the anisotropy of the emission and the rotational branch dependence of the fluorescence polarization are enhanced in double-resonance excitation schemes. In the present work, we analyze the relative intensities in the (7)Li(2) 1(3)Sigma(-)(g) --> 1(b)(3)Pi(u) and 1(3)Delta(g) --> 1(b)(3)Pi(u) resolved fluorescence spectra, observed following double-resonance excitation, for three different detection schemes. Copyright 1999 Academic Press.

Exposure to atmospheric radon

We measured radon (222Rn) concentrations in Iowa and Minnesota and found that unusually high annual average radon concentrations occur outdoors in portions of central North America. In some areas, outdoor concentrations exceed the national average indoor radon concentration. The general spatial patterns of outdoor radon and indoor radon are similar to the spatial distribution of radon progeny in the soil. Outdoor radon exposure in this region can be a substantial fraction of an individual's total radon exposure and is highly variable across the population. Estimated lifetime effective dose equivalents for the women participants in a radon-related lung cancer study varied by a factor of two at the median dose, 8 mSv, and ranged up to 60 mSv (6 rem). Failure to include these doses can reduce the statistical power of epidemiologic studies that examine the lung cancer risk associated with residential radon exposure.

Thermochemical Properties (D degrees0 and IP) of the Lanthanide Monohalides

Thermochemical data for the lanthanide monohalides have been combined with recent ligand field theory calculations (A. L. Kaledin, M. C. Heaven, R. W. Field, and L. A. Kaledin (1996). J. Mol. Spectrosc. 179, 310) to estimate the dissociation energies and ionization potentials for all LnX (where Ln in Ba through Lu, and X in F, Cl, Br, or I) molecules and the dissociation energies for the LnX+ ions. Owing to the negligible involvement of the core-like 4f electrons in bonding, the dissociation energies and ionization potentials of all LnX molecules, where Ln in Ba through Lu, and X in O, S, F, Cl, Br, or I, should vary with Ln atom in a simple linear manner, provided that corrections are made for differences in f-orbital occupancy between the LnX molecule and the free Ln atom or between the LnX molecule and the LnX+ molecular ion. We provide such a model here and, in so doing, correct several inconsistencies in the thermochemical data. Based on thermochemical data (A. A. Kitaev, I. S. Gotkis, P. G. Val'kov, and K. C. Krasnov (1996). Russ. Chem. Phys. 7, 1685) and recent spectroscopic observations (M. C. McCarthy, J. C. Bloch, R. W. Field, and L. A. Kaledin (1996) J. Mol. Spectrosc. 179, 251), a revised value for the ionization potential of DyF, IP(DyF) = 5.85 +/- 0.06 eV, is proposed. Copyright 1999 Academic Press.

Double-Resonance Spectroscopic Studies of Core-Penetrating Rydberg States of CaCl

Six core-penetrating Rydberg series have been assigned in the CaCl molecule by a combination of double-resonance spectroscopic techniques. Two 2Sigma+ series, with approximate quantum defects (delta) of 0.51 and 0.25, have been observed with effective principal quantum numbers (n*) in the range of 5-8 using the D2Sigma+ state as the resonant intermediate state for REMPI and/or ion-dip detection. A third 2Sigma+ series with delta approximately 0.84 and a 2Delta series with delta approximately 0.95 have been observed with n* = 16-18 using the A2Pi3/2 state as the resonant intermediate state for preparation of v+ = 1 vibrationally autoionizing states. Two additional series in the same region with delta approximately 0.90 and 0.07 are tentatively identified as the expected core-penetrating 2Pi series. Vibrational assignments have been confirmed in many cases on the basis of isotope shifts between the 35Cl and 37Cl isotopomers. The ion-dip and REMPI spectra display linewidths systematically broadened by predissociation. In addition to the assigned core-penetrating series, both the REMPI and the ion-dip spectra display some sharper features that have not yet been assigned. These sharper features most likely arise from perturbations of optically "bright" core-penetrating states by nominally "dark" higher-l core-nonpenetrating states. Copyright 1999 Academic Press.

The Predissociation Mechanism for 2Sigma+ Rydberg States of CaCl

This work summarizes experimental results from recent ion-dip spectroscopy studies of CaCl and from previously unpublished optical-optical double-resonance work with specific regard to predissociation processes of 2Sigma+ Rydberg states in the low n* (n* = 7, IP - En* = 2240 cm-1) region. A single repulsive state (assigned as 2Sigma+) was found to be responsible for all observed predissociations of 2Sigma+ Rydberg states. The n*-dependent internuclear distances of the intersections between Rydberg states and the repulsive 2Sigma+ state were determined through the use of trial-and-error Franck-Condon calculations. Values of energy-descaled electronic matrix elements governing the Rydberg left and right arrow repulsive state interaction were obtained from the measured linewidths (0.6 < Gamma < 1.2 cm-1) and computed Franck-Condon densities. Copyright 1999 Academic Press.

Spatial variation of residential radon concentrations: the Iowa Radon Lung Cancer Study

Homeowners and researchers frequently estimate the radon concentrations in various areas of the home from a single radon measurement often performed in the home's basement. This study describes the spatial variation of radon concentrations both between floors and between rooms on the same floor. The geometric mean basement and first floor radon concentrations for one-story homes were 13.8% and 9.0% higher, respectively, as compared to their counterparts in two-story homes. The median first floor/basement ratio of radon concentrations for one-story homes was 0.60. The median ratios between first floor/basement and second floor/basement for two-story homes were 0.51 and 0.62, respectively. The mean coefficient of variation for detectors placed on the same floor was 9.5%, which was only 2.6% higher than the mean coefficient of variation found for collocated (duplicate) quality control detectors. The wide individual variations noted in radon concentrations serve as a reminder of the importance of performing multiple radon measurements in various parts of the home when estimating home radon concentrations.

The 4(3)Pig and 6(3)Pig States of Na2: Observation and Assignment

Two 3Pig states of Na2 have been observed in the 35 000-38 000 cm-1 energy region by pulsed perturbation facilitated optical-optical double resonance (PFOODR) fluorescence excitation spectroscopy and assigned to the 5dpi and 6dpi (the fourth and sixth according to the energy rank at Re) 3Pig Rydberg states, respectively. Molecular constants and RKR potential curves are reported. Copyright 1998 Academic Press.

Retrospective temporal and spatial mobility of adult Iowa women

Human exposure assessments require a linkage between toxicant concentrations in occupied spaces and the receptor's mobility pattern. Databases reporting distinct populations' mobility in various parts of the home, time outside the home, and time in another building are scarce. Temporal longitudinal trends in these mobility patterns for specific age and gender groups are nonexistent. This paper describes subgroup trends in the spatial and temporal mobility patterns within the home, outside the home, and in another building for 619 Iowa females that occupied the same home for at least 20 years. The study found that the mean time spent at home for the participants ranged from a low of 69.4% for the 50-59 year age group to a high of 81.6% for the over 80-year-old age group. Participants who lived in either one- or two- story homes with basements spent the majority of their residential occupancy on the first story. Trends across age varied for other subgroups by number of children, education, and urban/rural status. Since all of these trends were nonlinear, they indicate that error exists when assuming a constant, such as a 75% home occupancy factor, which has been advocated by some researchers and agencies. In addition, while aggregate data, such as presented in this report, are more helpful in deriving risk estimates for population subgroups, they cannot supplant good individual-level data for determining risks.