Collision‐induced photon emissions from 8 ke V O and CO ion beams

Holmes, John L.; Mayer, Paul M.

doi:10.1002/jms.1190300110

Cited by 6 publications

(4 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[33][34][35][36][37][38][39][40] It has also been used previously in our lab to study ion-target gas collisions at 8 kV. 32,40,41 Due to the difference in the nature of the two excitation models presented above, they would lead to different results with respect to the emission intensities when collisions are performed at different ion translational energies. According to the vertical transition model, electronic transitions to various excited states take place simultaneously and in competition with each other.…”

Section: Introductionmentioning

confidence: 99%

“…For intermediate values of ξ, a branching takes place with a probability given by the Landau−Zener formula In our study, we use the technique of collision-induced emission (CIE) to probe the collision event in CID more thoroughly. This technique has been intensely used, especially on the study of N 2 − and CO 2 . − It has also been used previously in our lab to study ion-target gas collisions at 8 kV. ,, Due to the difference in the nature of the two excitation models presented above, they would lead to different results with respect to the emission intensities when collisions are performed at different ion translational energies. According to the vertical transition model, electronic transitions to various excited states take place simultaneously and in competition with each other.…”

Section: Introductionmentioning

confidence: 99%

“…This technique has been intensely used, especially on the study of N 2 13-32 and CO 2 . [33][34][35][36][37][38][39][40] It has also been used previously in our lab to study ion-target gas collisions at 8 kV. 32,40,41 Due to the difference in the nature of the two excitation models presented above, they would lead to different results with respect to the emission intensities when collisions are performed at different ion translational energies.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Experimental Evidence for the Curve Crossing Mechanism for Collisional Excitation in keV N₂^+•/He Collisions by Emission Spectroscopy

Poon

Mayer

2007

J. Phys. Chem. A

View full text Add to dashboard Cite

Collision-induced emission (CIE) experiments were carried out by coupling a spectrograph and charge-coupled device detector (CCD) to a commercial analytical mass spectrometer. An Einzel lens and a deceleration-reacceleration lens assembly as described in the current article were installed in the mass spectrometer to allow for the deceleration of the ions before collision. Collision-induced emission spectra of N2+*/He collisions at lab frame collision energies from 2 to 8 keV were obtained from 190-1020 nm. The emissions were assigned to the Deltav=+2, +1, 0, -1, -2 vibrational transition progression in the N2+* B 2Sigmau+-->X 2Sigmag+ electronic transition as well as some atomic lines from the fragments N+, N* and the target gas He. N2+* A 2u-->X 2Sigmag+ emission was also observed but was very weak due to the long lifetime of the A 2u state. The relative intensities of the N2+*, N, and N+ emissions are independent of the ion translational energy within the studied energy range. This observation supports the curve-crossing mechanism for collisional excitation, suggesting that a complicated sequence of curve-crossings takes place upon collisional activation.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Experimental Evidence for the Curve Crossing Mechanism for Collisional Excitation in keV N₂^+•/He Collisions by Emission Spectroscopy

Poon

Mayer

2007

J. Phys. Chem. A

View full text Add to dashboard Cite

show abstract

“…An initial study from our laboratory on the emissions of CO 2 ϩ· /He collisions from 190 to 680 nm also showed both B 2 ⌺ u ϩ ¡ X 2 ⌸ g and A 2 ⌸ u ¡ X 2 ⌸ g emission bands [23]. To our knowledge, collisioninduced emissions (CIE) resulting from the direct excitation of CO 2 ϩ· precursor ions has never been observed over a range of ion translational energies.…”

mentioning

confidence: 91%

Should a franck-condon or a curve-crossing picture be applied to ion-target collisional activation? A study of keV CO₂^+·/He collisions by emission spectroscopy

Poon

Mayer

2008

J. Am. Soc. Mass Spectrom.

View full text Add to dashboard Cite

Collision-induced photon emissions (CIE) were observed for keY COt/He collisions from 190 to 1020 nm. The emissions were assigned to the~v = 0 band of the CO;· B 2I: -'> X 2II g electronic transition and the~v = +3, +2, +1,0, -1, -2, -3 vibrational transition progression in the cot A 2II u -'> X zII g electronic transition. The other peaks arise from the emissions of excited 0' fragment atoms and the target gas. The relative intensities of the cot and 0' emissions are independent of the ion translational energy above 3 keY, supporting the curve-crossing mechanism for collisional excitation. Investigation of the relative intensities within the A -n, -'> X 2II g emission of cot indicates that the vibrational distribution is well described by the Franck-Condon [9,10]. This explanation, however, could not explain the similar behavior in the direct excitation process observed in Nt/target collisions [11]. Kelley et aL [8,12] later explained this phenomenon with a more general qualitative curve-crossing model based on the assumption that deviations from vertical transitions during collisions are caused by a short-range, repulsive interaction between the projectile and the target and that these short-range interactions result in the direct translational-vibrational excitation in both the initial and the final electronic states of the diatomic molecule [4, 8,12]. The fact that shortrange forces are involved means that the reaction occurs at small impact parameters. As such, the diatomic molecule cannot be regarded as being isolated. In other words, distortion occurs by chemical forces that are operative in any short-range encounter between two atoms or molecules. Landau and Zener expressed the probability (P) of crossing from one potential curve to another in terms of the slope (dV/dr) difference at the crossing point and the relative velocity (v) of the two colliding species [13,14]. D etection of photon emissions from collisionallyactivated species provides information on the electronic states that are accessible by collisions. This type of emission spectroscopy is often carried out in a mass spectrometer for the study of ion-neutral collisions where the projectile ions collide with a neutral target gas in a collision cell [1][2][3][4][5].Early experiments were carried out to acquire laboratory data on reactions that occur in the earth's atmosphere, in particular on the charge-transfer process. Consistency between experimental results with those predicted by Franck-Condon factors is often used as a sign that electronic transitions in the collision process are vertical [6][7][8]. Moore and Doering have studied the vibrational distribution of the N; B zI: state by observing the relative band intensities of the~v = -1 sequence of the B zI: -'> X zI; emission resulting from the charge-transfer of various projectile atomic/diatomic ions with N z [9]. They concluded that the observed vibrational distributions depend heavily on the laboratory velocity of the reactant ion but very little on its chemical nature. When the velo...

show abstract

Stabilität von gasförmigem Thalliummonofluorid: TlF⁰, TlF⁺ und TlF²⁺

et al. 2005

View full text Add to dashboard Cite

show abstract

Collision‐induced photon emissions from 8 ke V O and CO ion beams

Cited by 6 publications

References 38 publications

Experimental Evidence for the Curve Crossing Mechanism for Collisional Excitation in keV N₂^+•/He Collisions by Emission Spectroscopy

Experimental Evidence for the Curve Crossing Mechanism for Collisional Excitation in keV N₂^+•/He Collisions by Emission Spectroscopy

Should a franck-condon or a curve-crossing picture be applied to ion-target collisional activation? A study of keV CO₂^+·/He collisions by emission spectroscopy

Stabilität von gasförmigem Thalliummonofluorid: TlF⁰, TlF⁺ und TlF²⁺

Contact Info

Product

Resources

About

Collision‐induced photon emissions from 8 ke V O and CO ion beams

Cited by 6 publications

References 38 publications

Experimental Evidence for the Curve Crossing Mechanism for Collisional Excitation in keV N2+•/He Collisions by Emission Spectroscopy

Experimental Evidence for the Curve Crossing Mechanism for Collisional Excitation in keV N2+•/He Collisions by Emission Spectroscopy

Should a franck-condon or a curve-crossing picture be applied to ion-target collisional activation? A study of keV CO2+·/He collisions by emission spectroscopy

Stabilität von gasförmigem Thalliummonofluorid: TlF0, TlF+ und TlF2+

Contact Info

Product

Resources

About

Experimental Evidence for the Curve Crossing Mechanism for Collisional Excitation in keV N₂^+•/He Collisions by Emission Spectroscopy

Experimental Evidence for the Curve Crossing Mechanism for Collisional Excitation in keV N₂^+•/He Collisions by Emission Spectroscopy

Should a franck-condon or a curve-crossing picture be applied to ion-target collisional activation? A study of keV CO₂^+·/He collisions by emission spectroscopy

Stabilität von gasförmigem Thalliummonofluorid: TlF⁰, TlF⁺ und TlF²⁺