Vibrational spectra of N2: An advanced undergraduate laboratory in atomic and molecular spectroscopy

Bayram, Servet; Freamat, Mario

doi:10.1119/1.4722793

Cited by 47 publications

(34 citation statements)

References 17 publications

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“…This spectrometric study complements two other experiments treating the vibrational and rotational spectrometry of the diatomic molecule of nitrogen. 5,6 II. THEORETICAL BACKGROUND…”

Section: Introductionmentioning

confidence: 99%

A Spectral Analysis of Laser Induced Fluorescence of Diatomic Iodine

Bayram¹,

Freamat²

2015

2015 Conference on Laboratory Instruction Beyond the First Year

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When optically excited, diatomic iodine absorbs in the 490 to 650-nm visible region of the spectrum and, after radiative relaxation, it displays an emission spectrum of discrete vibrational bands at moderate resolution. This makes laser-induced fluorescence spectrum of molecular iodine especially suitable to study the energy structure of homonuclear diatomic molecules at room temperature. In this spirit, we present a rather straightforward and inexpensive experimental setup and the associated spectral analysis which provides an excellent exercise of applied quantum mechanics fit for advanced laboratory courses. The students would be required to assign spectral lines, fill a Deslandres table, process the data to estimate the harmonic and anharmonic characteristics of the ground vibronic state involved in the radiative transitions, and henceforth calculate a set of molecular constants and discuss a model of molecular vibrator.

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“…This spectrometric study complements two other experiments treating the vibrational and rotational spectrometry of the diatomic molecule of nitrogen. 5,6 II. THEORETICAL BACKGROUND…”

Section: Introductionmentioning

confidence: 99%

A Spectral Analysis of Laser Induced Fluorescence of Diatomic Iodine

Bayram¹,

Freamat²

2015

2015 Conference on Laboratory Instruction Beyond the First Year

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“…3 were not so high, only strong lines identified were atomic lines O 777.4 nm, 822.7 nm and N 746.6 nm, 868.6 nm20. The strong lines were recently being used for lasing21.…”

Section: Resultsmentioning

confidence: 99%

Intricate Plasma-Scattered Images and Spectra of Focused Femtosecond Laser Pulses

Ooi

Talib

2016

Sci Rep

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We report on some interesting phenomena in the focusing and scattering of femtosecond laser pulses in free space that provide insights on intense laser plasma interactions. The scattered image in the far field is analyzed and the connection with the observed structure of the plasma at the focus is discussed. We explain the physical mechanisms behind the changes in the colorful and intricate image formed by scattering from the plasma for different compressions, as well as orientations of plano-convex lens. The laser power does not show significant effect on the images. The pulse repetition rate above 500 Hz can affect the image through slow dynamics The spectrum of each color in the image shows oscillatory peaks due to interference of delayed pulse that correlate with the plasma length. Spectral lines of atomic species are identified and new peaks are observed through the white light emitted by the plasma spot. We find that an Ar gas jet can brighten the white light of the plasma spot and produce high resolution spectral peaks. The intricate image is found to be extremely sensitive and this is useful for applications in sensing microscale objects.

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“…Other OH lines (such as the band at 314 nm) were too weak to be detected in all the cases. Moreover, the emission due to the N2 transition C 3 Πu → Β 3 Πg [42, 45,46] The glow phase featured radiative emissions of CN and OH radicals [41][42][43][44]. As shown in Figure 11, only the highest emission band of the CN violet system B 2 Σ + → X 2 Σ + at 388 nm were resolved for both cases.…”

Section: Resultsmentioning

confidence: 99%

“…Other OH lines (such as the band at 314 nm) were too weak to be detected in all the cases. Moreover, the emission due to the N 2 transition C 3 Π u → B 3 Π g [42,45,46] resulted sufficiently intense to interfere with the CN (0, 0) band. An emission band around 336 nm due to the Energies 2017, 10, 1337 13 of 23 NH A 2 Σ + → X 2 Π electronic transition was also observed, but the intensity resulted too low for the retrieving procedure.…”

Section: Resultsmentioning

confidence: 99%

“…Other OH lines (such as the band at 314 nm) were too weak to be detected in all the cases. Moreover, the emission due to the N2 transition C 3 Πu → Β 3 Πg [42, 45,46] resulted sufficiently intense to interfere with the CN (0, 0) band. An emission band around 336 nm due to the NH Α 2 Σ + → The glow phase featured radiative emissions of CN and OH radicals [41][42][43][44].…”

Section: Resultsmentioning

confidence: 99%

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Flame Front Propagation in an Optical GDI Engine under Stoichiometric and Lean Burn Conditions

et al. 2017

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Lean fueling of spark ignited (SI) engines is a valid method for increasing efficiency and reducing nitric oxide (NO x ) emissions. Gasoline direct injection (GDI) allows better fuel economy with respect to the port-fuel injection configuration, through greater flexibility to load changes, reduced tendency to abnormal combustion, and reduction of pumping and heat losses. During homogenous charge operation with lean mixtures, flame development is prolonged and incomplete combustion can even occur, causing a decrease in stability and engine efficiency. On the other hand, charge stratification results in fuel impingement on the combustion chamber walls and high particle emissions. Therefore, lean operation requires a fundamentally new understanding of in-cylinder processes for developing the next generation of direct-injection (DI) SI engines. In this paper, combustion was investigated in an optically accessible DISI single cylinder research engine fueled with gasoline. Stoichiometric and lean operations were studied in detail through a combined thermodynamic and optical approach. The engine was operated at a fixed rotational speed (1000 rpm), with a wide open throttle, and at the start of the injection during the intake stroke. The excess air ratio was raised from 1 to values close to the flammability limit, and spark timing was adopted according to the maximum brake torque setting for each case. Cycle resolved digital imaging and spectroscopy were applied; the optical data were correlated to in-cylinder pressure traces and exhaust gas emission measurements. Flame front propagation speed, flame morphology parameters, and centroid motion were evaluated through image processing. Chemical kinetics were characterized based on spectroscopy data. Lean burn operation demonstrated increased flame distortion and center movement from the location of the spark plug compared to the stoichiometric case; engine stability decreased as the lean flammability limit was approached.

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Vibrational spectra of N2: An advanced undergraduate laboratory in atomic and molecular spectroscopy

Cited by 47 publications

References 17 publications

A Spectral Analysis of Laser Induced Fluorescence of Diatomic Iodine

A Spectral Analysis of Laser Induced Fluorescence of Diatomic Iodine

Intricate Plasma-Scattered Images and Spectra of Focused Femtosecond Laser Pulses

Flame Front Propagation in an Optical GDI Engine under Stoichiometric and Lean Burn Conditions

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