Investigation of positive and negative ionic products from laser ablation of polymers

Campbell, Eleanor E. B.; Ulmer, Gene C.; Hasselberger, B.; Hertel, I. V.

doi:10.1016/0169-4332(89)90237-7

Cited by 30 publications

(11 citation statements)

References 15 publications

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“…In particular, fairly strong peaks at 50, 51, and 74 ainu may indicate the formation of linear chain clusters of CaN and CsN, which is astrophysically of interest, consisting of odd numbers of carbon atoms attached to a nitrogen. In the laser ablation of polyimide, the peaks assigned to C3N +, CsN + [10], and C,N-(n = 3 -19; odd numbers) [14,15] have been observed. The peaks at 65, 77, 105, and 115 ainu may be associated with a C3N structure.…”

Section: Resultsmentioning

confidence: 99%

Laser-ionization mass-spectrometric studies on laser ablation of a nitrogen-rich polymer at 532 nm and 1064 nm

Kokai¹,

Koga

Kakudate

et al. 1994

Appl. Phys. A

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Abstract. Laser-ionization Time-Of-Flight (TOF) massspectrometric studies have been carried out on the 532 nm and 1064nm laser ablation products from a nitrogen-rich polymer. The polymer used had an elemental composition of C6.oNs.9H3. 4 and consisted of C = N , C --N , and N --H chemical bonds. The TOF mass spectra observed were composed of various peaks (_< 150 amu) depending on the ablation laser wavelength. The primary peaks were assigned to C +, CN +, CH,N (n = 1 -3) and C2H2N ;-for 532 nm ablation, and C +, C~, HCN +, HCCN +, C H 2 N H +, HNCN +, H 3 N C N + and C4HgN~ -for 1064nm ablation. The flight velocity distributions with peak velocities ranging from ~8.6 x 103 cm/s to ~3.8 x 104 cm/s were measured for these products. The distinct velocity distributions observed between small and large products indicate the presence of two origins in the fragment ejection process from the polymer for both 532 nm and 1064 nm ablation. Furthermore, we suggest an importance of the translational energy of the fragments for the product generation in the laser plume. PACS: 81.15, 82.80, 42.62 Numerous gaseous and solid products are generated by ultraviolet laser ablation of organic polymers [1]. The feature and abundance of the products depends strongly on the kind of polymer used and laser irradiation conditions such as wavelength, fluence, and pulse repetition rate. By means of mass spectrometry, extensive characterization of ablated gaseous products from several polymers have been performed [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Specifically, the primary products were identified and the flight velocity distribution of each product was determined. In addition, formation of large carbon clusters were detected and studied. The products detected were composed of both neutral and ionic species. The ratio of neutral to ionic species depended on the laser fluence at the polymer surface. At relatively lower fluences, most of the products were neutrals, which were characterized by quadrupole or laser-ionization Time-Of-Flight (TOF) mass spectrometry.The ablated neutral species from PolyMethylMethAcrylate (PMMA) have been measured with the use of a quadrupole mass spectrometer [2-4]. Danielzik et al.[2] have reported, for 193-nm ArF laser irradiation, the detection of MMA monomer with thermal MaxwellBoltzmann (fluence < 120 mJ/cm 2) and highly directional non Maxwell-Boltzmann (> 120 mJ/cm 2) velocity distributions. Estler and Nogar [3] have observed a dramatic change of ablation products from PMMA depending on the irradiation laser wavelength. At 266 nm and above, the products were dominated by monomer, CO2, and CO. At wavelengths below 266 nm, methyl formate appeared as a major product. Mass analysis was also carried out on the ablation products at 266 nm from tetrafluoroethylene, polycarbonate, and PolyStyrene (PS), in addition to PMMA [4]. Various small fragments and the PS monomer were detected.Laser-ionization TOF mass spectrometry has been employed to examine the ablation products from several polym...

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Section: Resultsmentioning

confidence: 99%

Laser-ionization mass-spectrometric studies on laser ablation of a nitrogen-rich polymer at 532 nm and 1064 nm

Kokai¹,

Koga

Kakudate

et al. 1994

Appl. Phys. A

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“…Initial velocity distributions generated from each of these two extreme situations, namely complete explosive ablation and limited superficial material removal, should in principle be experimentally differentiable with the DE method. For an explosive situation in which enough energy is delivered, one could reasonably expect that the ions formed would expand in a quasi‐spherical manner (similar to a spherical symmetrical Coulomb explosion mechanism, for instance 37. One can glimpse this kind of behavior in the above‐mentioned simulations, for large energies and small enough particles27).…”

Section: Discussionmentioning

confidence: 97%

Initial velocity distributions of ions generated by in‐flight laser desorption/ionization of individual polystyrene latex microparticles as studied by the delayed ion extraction method

Vera

Trimborn

Hinz

et al. 2004

Rapid Comm Mass Spectrometry

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The delayed ion extraction method has been used to study characteristics of the initial velocity distributions of positive and negative ions produced simultaneously by laser desorption/ionization (LDI) from non-impacted single aerosol polymeric particles, using a bipolar time-of-flight (TOF) instrument (LAMPAS 2). Due to the geometry of the setup and the characteristics of the ablation process, only the projections of the velocities on the axis of the mass spectrometer can be directly studied. Additionally, since the mean initial velocity under these conditions should be close to zero, it was necessary to extend the method by taking into account higher order contributions of the velocity distribution. Theoretical expressions for these higher order terms are presented and discussed. The bipolar characteristics of the instrument permit evaluation and treatment of a possible instrumental artifact caused by small inclinations of the ionizing laser with respect to the ideal incidence direction. Results of a number of experiments are presented and discussed in relation to the theoretical expressions presented, and to possible ablation scenarios. Evidence pointing out that, under our experimental conditions, only partial ablation of the latex particles occurs was obtained. The variance of the distribution of the projection of the initial velocities can be directly estimated from these results. By assuming that the total initial velocities of the ions are developed completely according to a single-temperature adiabatic expansion mechanism, temperatures of approximately 50 K/Da can be assigned to the ion clouds from the variance estimations. If a two-temperature model is used, a radial temperature of about 100 K/Da results. These values are in reasonable agreement with results for polymer ablation from the literature.

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“…Similar trends in average translational energies with increasing fragment mass has been re-ported for ionic fragments produced after the ablation of polyimide and polystyrene. 35,36) To confirm the presence of peaks corresponding to native ionic fragments produced by the ablation process, experiments were performed by applying a voltage pulse of +400 V to the V A2 grid of the TOF assembly at various delay times after the laser ablation pulse. The default voltage settings for both the V A1 and V A2 grids were 0 V, while the V A3 was grounded (Fig.…”

Section: High Laser Fluence Regime (F ≥ 100 Mj/cm 2 )mentioning

confidence: 99%

“…6) The polymers that have attracted the greatest interest are poly(methyl methacrylate) (PMMA), 7,[11][12][13][14] and polyimide. 18,20,35,36) Aromatic polysulfones, such as polyarysulfone (PAS), polyethersulfone (PES) and polysulfone (PS) have attained considerable importance owing to their suitability for the fabrication of ultrafiltration and microfiltration membranes, 23) as well as in various ap-ucts were identified and found to depend strongly on ablation fluence. Arrival distributions for the ablation products were obtained by changing the delay time of the ionization laser with respect to the ablation laser.…”

Section: Introductionmentioning

confidence: 99%

Numerical Analysis for the Application of Electric Current to Silicon Semiconducting Materials

Wang¹

2005

Jpn. J. Appl. Phys.

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Neutral fragments from the 248 nm laser ablation of polyarylsulfone (PAS) were investigated using laser post ionization (193 nm) time-of-flight (TOF) mass spectroscopy. Three regimes of ablation fluence were distinguished with respect to detected fragments and differences in their velocity distributions. Over the entire fluence range the arrival profiles of the products matched with a shifted Maxwell-Boltzmann distribution. Interestingly, average translational velocities revealed a nonmonotonical dependency on ablation fluence. This is probably be due to screening effects of the ablation pulse by the plume, or to non-thermal effects that may contribute to the ablation process at high fluences. The dependencies of both the flight velocities and the Knudsen layer temperature of the fragments on fluence suggest that PAS ablation is photothermally driven. However, the excessively high values for average translational energies (up to 34 eV at high fluences) and their increases with increasing fragments amu indicate that the process also has some non-thermal features.

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Investigation of positive and negative ionic products from laser ablation of polymers

Cited by 30 publications

References 15 publications

Laser-ionization mass-spectrometric studies on laser ablation of a nitrogen-rich polymer at 532 nm and 1064 nm

Laser-ionization mass-spectrometric studies on laser ablation of a nitrogen-rich polymer at 532 nm and 1064 nm

Initial velocity distributions of ions generated by in‐flight laser desorption/ionization of individual polystyrene latex microparticles as studied by the delayed ion extraction method

Numerical Analysis for the Application of Electric Current to Silicon Semiconducting Materials

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