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Full-Text Articles in Physics
Photoexcitation And Photoionization From The 2p53p[5/2]2,3 Levels In Neon, M. Baig, I. Bokhari, M. Rafiq, M. Kalyar, T. Hussian, Raheel Ali, Naveed Piracha
Photoexcitation And Photoionization From The 2p53p[5/2]2,3 Levels In Neon, M. Baig, I. Bokhari, M. Rafiq, M. Kalyar, T. Hussian, Raheel Ali, Naveed Piracha
Naveed K. Piracha
We present measurements of the excitation spectra from the 2p53p [5/2]3,2 levels in neon using two-step laser excitation and ionization in conjunction with an optogalvanic detection in dc and rf discharge cells. The 2p53p [5/2]3,2 intermediate levels have been approached via the collisionally populated 2p53s [3/2]2 metastable level. The Rydberg series 2p5(2P3/2)nd [7/2]4 (12 ⩽ n ⩽ 44), 2p5(2P3/2)ns [3/2]2 (13 ⩽ n ⩽ 35) and the parity forbidden transitions 2p5(2P3/2)np [5/2]3 (13 ⩽ n ⩽ 19) have been observed from the 2p53p [5/2]3 level, whereas the 2p5(2P3/2)nd [7/2]3 (12 ⩽ n ⩽ 44), 2p5(2P3/2)ns [3/2]2 (13 ⩽ n ⩽ …
Laser Excited Population Redistribution In The 2p^53p Multiplet In Neon, Naveed Piracha, K. Duncan-Chamberlain, R. Ali, M. Kalyar, M. Mehmood, R. Ahmed, M. Baig
Laser Excited Population Redistribution In The 2p^53p Multiplet In Neon, Naveed Piracha, K. Duncan-Chamberlain, R. Ali, M. Kalyar, M. Mehmood, R. Ahmed, M. Baig
Naveed K. Piracha
Using neon hollow cathode lamp and employing laser optogalvanic technique, we have studied population redistribution in the 2p^53p multiplet. The spectra recorded in the laser energy region of 23300cm^-^1 -23600cm^-^1 show transitions originating from both the laser excited levels as well as from an adjacent level whose population builds up as a result of collisional deactivation. Employing the optical delay technique, we have been able to extract decay rates associated with the collisional population mixing of the p levels.
Measurements Of Electron Density, Temperature And Photoionization Cross Sections Of The Excited States Of Neon In A Discharge Plasma, Shaukat Mahmood, Nek Shaikh, M. Kalyar, Naveed Piracha, M. Baig
Measurements Of Electron Density, Temperature And Photoionization Cross Sections Of The Excited States Of Neon In A Discharge Plasma, Shaukat Mahmood, Nek Shaikh, M. Kalyar, Naveed Piracha, M. Baig
Naveed K. Piracha
In the present work emission and absorption spectroscopy have been used to determine the plasma parameters of neon in a hollow cathode discharge lamp. The excitation temperature is determined using the intensity ratio method and Boltzmann’s plot method whereas the electron density is determined from the Stark broadening of the spectral lines. The behavior of the optogalvanic signal as a function of laser energy has been studied for three transitions from the 2p53s [1/2]2 metastable state following ΔJ=ΔK=0, ±1 dipole selection rules. The saturation technique has been used to measure the photoionization cross section from three intermediate states 2p53p′ [1/2]1, …
The Study Of The 1s4–2pj Optogalvanic Transients In A Neon Discharge Plasma, Naveed Piracha, R. Feaver, T. Gilani, Rizwan Ahmed, R. Ali, M. Baig
The Study Of The 1s4–2pj Optogalvanic Transients In A Neon Discharge Plasma, Naveed Piracha, R. Feaver, T. Gilani, Rizwan Ahmed, R. Ali, M. Baig
Naveed K. Piracha
Time dependent optogalvanic signals induced by the 1s4→2pj laser excitations have been studied in neon DC plasma. The decay rates related to all the four 1si levels have been derived by fitting the waveforms with a mathematical rate equation model. The temporal signatures of three transitions namely 638.3, 650.7 and 724.5nm related to the 2p7, 2p8 and 2p10 upper levels, respectively, have been found to be different from the rest of the transitions. We relate these effects to the population redistribution of decaying channels and to the processes responsible for the optogalvanic effect.
The Study Of Optogalvanic Effect Associated With The 1s States Of Neon, Naveed Piracha, K. Nesbett, S. Marotta
The Study Of Optogalvanic Effect Associated With The 1s States Of Neon, Naveed Piracha, K. Nesbett, S. Marotta
Naveed K. Piracha
We report on the temporal evolution of the optogalvanic signals in neon using a commercial hollow cathode lamp in conjunction with a Nd:YAG pumped dye laser system. We have recorded transitions excited from each of the neon 1s states over a range of discharge current to investigate the dominant physical processes responsible for the optogalvanic effect in neon discharges. The decay rates associated with the four 1s levels have been obtained using a mathematical rate equation model. A linear relationship between the decay rates and the discharge current has been found and the effective lifetimes and the electron collisional rate …
On The Time-Resolved Optogalvanic Spectra Of Neon And Krypton, Naveed Piracha, K. Nesbett, S. Moten, P. Moeller
On The Time-Resolved Optogalvanic Spectra Of Neon And Krypton, Naveed Piracha, K. Nesbett, S. Moten, P. Moeller
Naveed K. Piracha
In this work time resolved optogalvanic signals associated with transitions excited from the first metastable state of neon and krypton have been studied. These gases have similar energy state configurations and it is of significant interest to study their time resolved optogalvanic waveforms resulting from transitions belonging to the states of same quantum numbers. The experimentally observed optogalvanic signals recorded for different discharge currents have been fitted to a theoretical model to obtain parameters that determine amplitudes, instrumental time constants and decay rates of the 1s levels.
Infrared Depletion Spectroscopy Of Aniline–Toluene Cluster: The Investigation Of The Red Shifts Of The Nh2 Stretching Vibrations Of Aniline–Aromatic Clusters, Naveed Piracha, F. Ito, T. Nakanaga
Infrared Depletion Spectroscopy Of Aniline–Toluene Cluster: The Investigation Of The Red Shifts Of The Nh2 Stretching Vibrations Of Aniline–Aromatic Clusters, Naveed Piracha, F. Ito, T. Nakanaga
Naveed K. Piracha
The infrared spectra of the NH2 stretching vibrations of aniline–toluene cluster and corresponding cluster cation have been measured by the infrared depletion method. The NH2 stretching vibrations of aniline–toluene cluster were observed at 3393 and 3468 cm−1. The red shifts from the corresponding bands of aniline monomer are 29 and 40 cm−1, respectively, for the NH2 symmetric and anti-symmetric stretching vibrations. The magnitudes of the red shifts are similar to those of other aniline–aromatic clusters. The structure of this cluster has been found to be a sandwich type, that is, the two aromatic rings are parallel in the cluster and …
Infrared Depletion Spectroscopy Of Aniline-Acetonitrile Cation And Aniline-Acetonitrile-Water Cation Clusters, H. Nagai, Naveed Piracha, T. Nakanaga
Infrared Depletion Spectroscopy Of Aniline-Acetonitrile Cation And Aniline-Acetonitrile-Water Cation Clusters, H. Nagai, Naveed Piracha, T. Nakanaga
Naveed K. Piracha
The vibrational spectra of the aniline-acetonitrile^+ and the aniline-acetonitrile-water^+ cluster cations have been measured by the infrared depletion spectroscopy in the frequency region of NH and OH stretching vibrations. One absorption band was observed at 3437cm^-^1 in the infrared spectrum of the aniline-acetonitrile^+ cluster cation, and was assigned to the NH stretching vibration of free NH of aniline. As for the aniline-water-acetonitrile^+ cluster cation, three absorptions were observed at 3722, 3634 and 3247cm^-^1, which were assigned to the anti-symmetric stretching and symmetric stretching vibrations of OH of water and the stretching vibrations of NH bond interacting with water, respectively. In …
Infrared Spectroscopy Of Aniline–Ne Clusters And The Corresponding Cluster Cations In The Nh2-Stretching Vibration Region, Naveed Piracha, T. Nakanaga
Infrared Spectroscopy Of Aniline–Ne Clusters And The Corresponding Cluster Cations In The Nh2-Stretching Vibration Region, Naveed Piracha, T. Nakanaga
Naveed K. Piracha
The vibrational spectra of the NH2-stretching modes of aniline–Ne and aniline–Ne+ have been measured using infrared depletion spectroscopy and REMPI–TOF mass spectrometry. In the NH2-stretching vibration region of the aniline–Ne clusters, two absorption bands at 3422 and 3508cm−1 were observed. The frequency shifts from the monomer was found to be negligibly small. As for the aniline–Ne+ cluster cations, the observed frequencies of the vibrational modes were 3394 and 3488cm−1. These values agreed with ones observed for aniline–Ar+ cluster within the error limit. This fact suggests that the effect of neon to aniline in forming the cluster is not significant in …
The Evidence Of The Mode Selectivity Of The Infrared Predissociation Reaction Of The Hydrogen Bonds In The Aniline–Water–Pyrrole Cluster Cation, Taisuke Nakanaga, Naveed Piracha, Fumiyuki Ito
The Evidence Of The Mode Selectivity Of The Infrared Predissociation Reaction Of The Hydrogen Bonds In The Aniline–Water–Pyrrole Cluster Cation, Taisuke Nakanaga, Naveed Piracha, Fumiyuki Ito
Naveed K. Piracha
The infrared spectrum of aniline–water–pyrrole cluster cation has been measured in the 3 μm region. Four strong vibrational bands were observed at 3313, 3515, 3637, and 3721cm−1, and the cluster dissociated into fragments in two reaction paths, AWP+→AW++P and AWP+→AP++W (A: aniline, W: water, P: pyrrole) when it absorbed an infrared photon. The branching ratio (AW+/AP+) has been determined to be 0.20±0.02 for the NH stretching vibration of aniline (3313cm−1, hydrogen-bonded to pyrrole) and 0.14±0.03 for the other three bands. This vibrational mode dependence should be due to the fast energy transfer from the NH to the intermolecular vibration through …
Investigation Of The Structure Of T He Ternary Cluster Of Aniline−Water−Tetrahydrofuran And Its Cation By Infrared Depletion Spectroscopy, Taisuke Nakanaga, Naveed Piracha, Fumiyuki Ito
Investigation Of The Structure Of T He Ternary Cluster Of Aniline−Water−Tetrahydrofuran And Its Cation By Infrared Depletion Spectroscopy, Taisuke Nakanaga, Naveed Piracha, Fumiyuki Ito
Naveed K. Piracha
No abstract provided.
Two-Photon Optogalvanic Spectra Of Argon: Odd Parity Rydberg States, Naveed Piracha, M. Baig, S. Khan, B. Suleman
Two-Photon Optogalvanic Spectra Of Argon: Odd Parity Rydberg States, Naveed Piracha, M. Baig, S. Khan, B. Suleman
Naveed K. Piracha
Extensive new data on the odd-parity, single-colour, two-photon optogalvanic spectra of argon in the visible region is reported using an excimer-pumped dye laser in conjunction with an argon discharge cell. The experimental technique enables us to record a pure two-photon spectrum in a region which is dominated by one-photon transitions. A large number of two-photon transitions, originating from the two metastable states [...] and [...] to the excited states of configurations [...] (J=0, 2) and [...] (J = 0 - 4) of argon, has been recorded and arranged into 10 Rydberg series. The interchannel interactions among the [...] and the …