Tesla Discharge Research Articles

Real-time detection of viruses in aerosols with weak light imaging based on Tesla discharge

The analysis and detection of nucleic acid and specific antigens and antibodies are the most basic technologies for virus monitoring. However, the potential window for applying these technologies exists within a late specific period in the early monitoring and control of unknown viruses, especially human and animal pathogenic viruses transmitted via aerosols, e.g., SARS-CoV-2 and its variants. This is because early, real-time, and convenient monitoring of unknown viruses in the air or exhaled gas cannot be directly achieved through existing technologies. Herein, we report a weak light spectral imaging technology based on Tesla discharge (termed T-DAI) that can quickly monitor for viruses in real time in simulated aerosols with 71% sensitivity and 76% specificity for aerosol virus concentrations exceeding approximately 2800 vp/μl. This technology realizes the rapid detection of low concentrations of viruses in aerosols and could provide an important means for predicting, screening, and monitoring unknown or pandemic pathogenic viruses in the air or exhaled breath of humans and animals.

Determination of intramolecular isotope distribution of ozone by oxidation reaction with silver metal

The intramolecular distribution of 17O in ozone was determined by a new technique using oxidation reaction of ozone with silver and measuring the isotope ratios 18O/16O and 17O/16O of silver oxide, ozone and leftover oxygen. These data along with known 18O distribution in ozone given by Janssen (2005) in terms of r50 = [16O16O18O]/[16O18O16O] allow us to determine r49 = [16O16O17O]/[16O17O16O]. It is seen that r49 values increase from 2.030 to 2.145 with increase of bulk 17O enrichment in ozone from 11.7‰ to 106.3‰ (controlled by varying temperature and pressure during ozone formation) just as r50 values increase from 1.922 to 2.089 with increase in bulk 18O enrichment over the same range. Over bulk enrichment level up to ∼100‰ the r49 values are higher than r50 values by 0.075 ± 0.026. The difference is small but significant since it corresponds to a large change in enrichment values of the asymmetric and symmetric types of 17O16O2 and 18O16O2 relative to a hypothetical ozone standard with statistical isotope distribution. The difference reduces with increase in bulk ozone enrichment. We do not find any significant variation in r values between ozone samples made by Tesla discharge and by UV photolysis of oxygen. Additionally, for ozone samples with negligible enrichment, the symmetrical isotopomers have relatively more heavy isotopes than the asymmetrical ones consistent with their bond strength difference. Atmospheric implications of the results are briefly discussed.

Direct-fitting approach to the analysis of high-resolution optical spectra: Monte Carlo and experimental studies of OH A(0)→X(0) spectra

The traditional approach for analyzing high-resolution optical spectra involves locating and measuring line frequencies, then assigning and fitting these to an appropriate model for the molecular energy levels. The alternative approach of fitting the spectrum directly is particularly appealing in the case of congested spectra with many overlapped features. The capabilities and limitations of direct fitting are explored in application to the 0–0 band of the OH A→X transition, as recorded on a charge-coupled-device array using a high-pressure Tesla discharge source. Monte Carlo calculations confirm that for Poisson (counting) data, the parameter errors from the variance–covariance matrix are trustworthy, unless weights are neglected, in which case the error estimates can be wildly optimistic. In the fitting of actual spectra, a major barrier is the derivation of a suitable instrumental line-shape function. In particular, the often adopted triangular slit function is grossly inadequate. A systematic procedure has been devised for obtaining the line shape as a sum of Gaussian and Lorentzian components. This method has facilitated the analysis of experimental spectra spanning the region 3071–3103 Å. A model having 46 adjustable parameters determines the temperature (320 K) of the low-N′ levels of the A state with σ < 1 K and corroborates theoretical intensity branching ratios within 2%. It also determines within 10% the contribution to the emission from OD, which is present in natural abundance (H:D≈7000) in the source.

TheD′ ↔ A′Transition in ClF

TheD′ (23P2) ↔A′(23Π) transition in ClF is studied in emission, in fluorescence, and through OODR excitation experiments. The emission spectrum is excited in a flowing Tesla discharge of ClF in half an atmosphere of Ar and is photographed at high resolution. The excitation and fluorescence spectra are obtained by pumping through perturbed levels of theB(0+3Π) valence state. The emission data yield a detailed characterization ofv′ levels 0 and 1 andv″ levels 3–8. The excitation spectra extend thev′ range tov′ = 16 and put both states on an absolute energy scale. The low-resolution fluorescence spectra spanv″ = 1–17, the upper limit of which lies within ∼20 cm−1of dissociation. Key spectroscopic parameters (cm−1) from the study, valid for35Cl19F, are:T′e= 55253, ω′e= 365.22, ωex′e= 2.005,T″e= 18257, ω″e= 363.53, ωex″e= 8.30,B′e= 0.21790,a′e= 0.00175,B″e= 0.33412,a″e= 0.00631,R′e= 2.5069 Å,R″e= 2.024 Å. A near-dissociation fit of theD′ →A′ emission and fluorescence data locates the first dissociation limit at 21495(5) cm−1, which is lower than the accepted value, but by just one standard error.

The B(1/2 2P3/2)→X(1/2 2Σ+) transition in XeI

The B(1/2 2P3/2)→X(1/2 2Σ+) transition in XeI (2385–2490 Å) is recorded at high resolution for the single isotopomer 136Xe127I, using a Tesla discharge source and a CCD array detector. The high signal-to-noise capabilities of the detector make it possible to measure the discrete vibrational structure in this system for the first time. The assignments consist of 86 v′–v″ bands spanning 15 upper-state levels (assigned as v′=3–17) and 17 lower-state levels (tentatively assigned as v″=0–16). A vibrational analysis yields the following spectroscopic constants (cm−1): ΔTe=40 047.8, ωe′=110.6, ωexe′=0.217, ωe″=24.0, ωexe″=0.66. From a near-dissociation analysis, the X state has a dissociation energy (𝒟e) of 267±5 cm−1 and supports 28 bound vibrational levels. However, it is likely that our lowest observed v″ level is not v″=0, so these values should be considered lower limits. The potential energy curves are modeled by a Morse–RKR function for the X state and a Rittner function for the B state. Trial-and-error Franck–Condon calculations are used to locate the B- and X-state potential curves relative to each other, fixing the X-state internuclear distance Re at a value ∼0.7 Å larger than that for the B state. Bound–free simulations of the low-resolution spectrum indicate that the X potential must be significantly steeper in the Franck–Condon region than found from previous scattering studies.

The B(1/2 2P3/2)→X(1/2 2Σ+) transition in XeBr

The B(1/2 2P3/2)→X(1/2 2Σ+) transition in XeBr is recorded at high resolution, using a CCD array detector to record spectra from Tesla discharge sources containing isotopically pure 136Xe with 81Br2 or 79Br2. The high signal/noise capabilities of the detector permit the measurement of discrete vibrational structure in this system, which has normally been treated as a purely bound–free transition. The assignments comprise 119 υ′–υ″ bands for 136Xe81Br and 86 for 136Xe79Br, spanning υ′=0–33 and υ″=0–16. The van der Waals ground state is analyzed through fits to the customary polynomials in (υ+1/2) and to near-dissociation expansions. Franck–Condon calculations are used to locate the X-state potential on the internuclear axis relative to the B state, which is modeled as a Rittner potential. The following fundamental spectroscopic constants (units cm−1, for 136Xe81Br) are obtained from the analysis: Te′=35 863.2, ωe′=135.72, ωexe′=0.32, ωe″=25.7, ωexe″=0.62. The ground state has a dissociation energy 𝒟e″=254±2 cm−1 and supports 24 bound vibrational levels.

High-resolution spectroscopy with a CCD array detector: The B → X transition in 136Xe 81Br

The B( 1 2 2P 3 2 )→X( 1 2 2Σ +) transition in XeBr is recorded at high resolution for the single isotopomer 136Xe 81Br, using a high-pressure tesla discharge source and a CCD array detector. The high signal/noise capabilities of the detector permit the first measurements of discrete vibrational structure in this system, which has previously been treated as a purely bound-free transition. The assignments comprise 115 v′- v″ bands spanning v′= 1–30 and v″ = 0–15 and yield the following fundamental spectroscopic constants (units cm −1): T′ e = 35862.6, (ω' e = 135.80, ω e X′ e = 0.36, ω″ e = 25.7, ω e x′ e = 0.65, and D″ e = 252.

High-resolution spectroscopy with a CCD array detector: application to the 2880 Å emission band system in I2

The 2880 Å system in the Tesla discharge spectrum of I2 in Ar is reexamined using a CCD array detector to record spectra for both 127I2 and 129I2. This charge-transfer transition terminates on a weakly bound valence state, giving a highly congested spectrum with fine violet-degraded band structure barely perceivable on a pseudocontinuous background. The superior signal-to-noise capabilities of the array detector permit a great improvement in the precision and number of measured bandheads, as compared with previous results obtained from photographically recorded spectra. The new data span a larger range of vibrational levels in the lower state and lead to a change in the previous ν″ numbering by −3 units. Both states can now be located precisely on the absolute energy axis through least-squares fits in which the lower state energy is represented as a near-dissociation expansion. The primary spectroscopic constants (cm−1) are [Formula: see text] [Formula: see text] [Formula: see text] [Formula: see text] [Formula: see text] [Formula: see text] The lower state has a dissociation energy of 287.5 cm−1 and supports 35 bound levels, subject, however, to possible further revision due to a remaining uncertainty of 1 unit in the ν″ numbering. The previous tentative electronic assignment of this system remains in effect: The upper state is likely the [Formula: see text] state that correlates with I−(1S) + I+(3P1), while the lower state is the [Formula: see text] component of the lowest valence 3Πu multiplet.

The G → A transition in ICl

The G[1( 3P 1)] → A 3 Π 1 band system of ICl (3250–3400 Å) is photographed at high resolution from tesla discharge sources containing the individual isotopomers, I 35Cl and I 37Cl. The rotational analysis of 24 v′- v″ bands includes ∼1700 assigned lines spanning v′ = 0–2 and v″ = 8–15. Most of the data involve the previously unreported v′ = 0 level of the G state, for which higher v levels have been studied before but not in this emission spectrum. The analysis generally corroborates the previous descriptions of both states.

The f → X transition in ICl

The f0 +( 3P 0) → X 1 Σ + band system of ICl (3000–3300 Å) is photographed at high resolution from tesla discharge sources containing the individual isotopomers, I 35Cl and I 37Cl. The rotational analysis of 24 v′- v″ bands includes ∼ 1900 assigned lines spanning v′ = 0–2 and v″ = 39–50. The data yield and improved description of the probed regions of both states, which have been observed before but not in this emission transition. Recommended constants for the f state (valid for v = 0–14, units cm −1) are: T e = 44 924.375, ω e = 184.158, ω e x e = 0.7439, ω e y e = 0.00268, B e = 0.057925, α e = 2.32 × 10 −4, γ e = 5.4 × 10 −7.

The emission of BrCl: Analysis of the D′ → A′ and E → B transitions

The emission spectrum of BrCl in Ar is studied using Tesla discharge sources containing single isotopomers of BrCl. The D′(2 3P 2) → A′ ( 3Π 2) and E(0 + 3P 2) → B( 3Π 0+) transitions are identified and analyzed, yielding the following values (cm −1) for the fundamental constants of the new states: A′: T e≈14700, ω e=232, R e=2.55 Å; D′: T e≈48400, ω e=197.9, R e=3.113 Å; E: T e=48760, ω e=196, R e≈3.05 Å.

Identification and analysis of the D' →A' transition in the emission spectrum of Cl 2

The emission spectrum of Cl 2 in Ar is re-examined using Tesla discharge sources containing isotopically pure 35Cl 2 and 37Cl 2. Earlier speculation that the dominant emission near 2580 Å is due to the D' 2 g( 3P 2 → A' 2 u( 3Π) transition is confirmed, with the following constants (cm −1) obtained for these states: Δ T e=40125.4, ω′ e = 253.17, ω″ e = 257.27. A weaker band system in the same spectral region is tentatively assigned to β 1 g( 3P 2) → A 1 u( 3Π).

Radiative lifetimes of metastable states of free radicals. II. PF b 1Σ + and CO a 3Π

Metastable CO a 3Π and PF b 1Σ + radicals were generated by a pulsed Tesla discharge technique in dilute mixtures of CO 2 and of PF 3 in Ar. For CO a 3Π, ν′ = 0 the averaged radiative lifetime τ rad for the a-X transition. was determined to be (7.9 ± 1.5) ms, and the quenching rate coefficients ( k M cm 3 s −1) obtained were k CO 2 < 3 × 10 −11 and k Ar = (2.3 ± 0.5) × 10 −16, in good agreement with previous determinations by other techniques. For PF b 1Σ +, ν′ = 0 the measurements yielded τ rad = (6.2 ± 0.7) ms, k PF 3 < 5 × 10 −13 and k Ar < 1 × 10 −17. From this value for τ rad a magnitude of (2.2 ± 0.2) × 10 −4 D 2 is calculated for the square of the transition moment, | R e| 2, for PF b 1Σ +-X 3Σ. The transition moment is an order of magnitude larger than that for the corresponding NF transition; reasons for this difference are discussed. The analogous transitions of O 2 and NCl also are considered.

Radiative lifetimes of metastable states of free radicals. I. NF b 1Σ +

Metastable excited NF b 1Σ + radicals were generated by means of a pulsed Tesla discharge in a slowly-flowing dilute mixture of NF 3 or N 2F 4 in argon. The excited NF radicals are believed to be generated by energy transfer between Ar 3P 0,2 metastable atoms and NF 3 (or N 2F 4). The decay of NF spontaneous emission near 530 nm, b 1Σ +(υ′=0)-X 3Σ(υ″=0), was used to determine the lifetime of NF b 1Σ +. The results gave a radiative lifetime τ rad equal to (22.6±1.7)×10 −3s (95% confidence limit). The square of the electronic transition moment | R e| 2 was calculated to be (2.1 ± 0.2)×10 −5 D 2 . Rate coefficients ( k M) for quenching of NF b 1Σ + were found to be k NF, = (1.8 ± 0.7) × 10 −12 cm 3 s −1 and k Ar<1 × 10 −17 cm 3 s −1. The method described here is expected to be useful for the study of other excited states whose lifetimes are inthe range 300 μs to 1 s.

Energy ordering of the B and C states in XeCl, XeBr, and KrCl, from temperature dependence of emission spectra

Inert-gas halide emission spectra from a Tesla discharge are studied as a function of pressure and temperature. From the temperature dependence of the infinite pressure ratio of broad-band (C → A and B → A) emission to B → X emission, the energy separations, T eC - T eB, are found to be −130 cm −1 (XeCl), −80 cm −1 (XeBr) and 375 cm −1 (KrCl). Estimates of the (C → A)/(B → X) spontaneous emission branching ratios agree well with theoretical predictions.

The tesla discharge as a spectroscopic source for the study of excimer laser transitions

The tesla discharge as a spectroscopic source for the study of excimer laser transitions

The tesla discharge as a spectroscopic source for the study of excimer laser transitions

A method for studying the pressure and temperature dependence of rare gas halide and halogen emissions is described. The tesla discharge utilized in this method is characterized in detail with respect to its temporal behavior and its radiant output. The light is found to be produced in moderately intense pulses as short as 0.5 micros in duration. Average dc radiant powers for strong emitters can exceed 5 mW. The method appears suitable for the study of most emitters that can be produced by electron beam excitation.

Emission spectrum of rare gas dimers in the vacuum UV region. II. Rotational analysis of band system I of Ar2

The emission spectrum of Ar2 excited by a Tesla discharge has been photographed at high resolution in the region 1073.5–1081.5 Å by 6.65 m spectrograph. Experimental conditions were chosen to produce only the band system emitted in the transition from the lowest excited state to the ground state. Rotational analyses of several bands indicate that the coupling scheme in the lowest excited state is closer to Hund–Mulliken case b than to case c, so that the excited state symmetry may be assigned approximately as 3Σ+u rather than 1u, 0−u. Rotational constants obtained for seven high-lying emitting levels with consecutively decreasing vibrational quantum numbers range from 0.073 to 0.105 cm−1. An attempt has been made to use spectroscopic results to depict the shapes and positions of the long range portions of the potential curves of the first two excited states (3Σ+u and 1Σ+u) of Ar2 relative to each other and to that of the ground state X 1Σ+g.

Temperatures of Tesla discharges from OH A → X intensity measurements

The OH A 2Σ + → X 2Π system is used as a diagnostic tool for temperature measurements of Tesla discharges in Ar and He seeded with 0.5 torr H 2O. From relative intensities of low- N′ lines in the 0-0 band we obtain temperatures which are independent of pressure for the range 100–650 torr and which are only a few degrees higher than the estimated wall temperatures. A check on the theoretical line strengths for OH A → X shows 1% agreement for main-branch transitions but only 5% agreement for satellite lines. Self-absorption problems are encountered and corrected for in the He discharge work; from the ≈10% magnitude of the correction, there are significant amounts (8 mtorr) of ground-state OH produced in the He Tesla discharge.

The excitation and quenching of N(2P)

The rate coefficients for quenching N(2P) by N, O, NO, CO, H2, O2, N2O, and CO2 have been measured by following the decay of emission from N(2P) excited in a Tesla discharge by energy transfer from N2(A 3Σ+u). Some of these results differ considerably from those in the literature.