Mass spectroscopic studies of the ArF-laser photoablation of polystyrene

Feldmann, D.; Kutzner, J.; Laukemper, J.; Macrobert, S; Welge, K. H.

doi:10.1007/bf00694197

Cited by 73 publications

(50 citation statements)

References 13 publications

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“…This is not a unreasonable approximation because the quantum yield with 193 nm photons is close to unity for production of monomers, which are the dominant photoproduct in the low fluence regime used in this study. 32,33 Simple collision theory predicts that 35 nm nanospheres will homogeneously nucleate in 100 µs. The particles measured at this condition have a mean diameter of approximately 25 nm, so we estimate the volume lost at 33%, which is close to the measured value (35%).…”

Section: Discussionmentioning

confidence: 99%

Photochemical Interaction of Polystyrene Nanospheres with 193 nm Pulsed Laser Light

et al. 2005

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The photochemical interaction of 193 nm light with polystyrene nanospheres is used to produce particles with a controlled size and morphology. Laser fluences from 0 to 0.14 J/cm 2 at 10 and 50 Hz photofragment nearly monodisperse 110 nm spherical polystyrene particles. The size distributions before and after irradiation are measured with a scanning mobility particle sizer (SMPS), and the morphology of the irradiated particles is examined with a transmission electron microscope (TEM). The results show that the irradiated particles have a smaller mean diameter (∼25 nm) and a number concentration more than an order of magnitude higher than nonirradiated particles. The particles are formed by nucleation of gas-phase species produced by photolytic decomposition of nanospheres. A nondimensional parameter, the photon-to-atom ratio (PAR), is used to interpret the laser-particle interaction energetics.

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Section: Discussionmentioning

confidence: 99%

Photochemical Interaction of Polystyrene Nanospheres with 193 nm Pulsed Laser Light

et al. 2005

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“…For several polymers such as polystyrene, Teflon, and poly(methyl methacrylate) (PMMA), MaxwellBoltzmann distributions were obtained, yielding temperatures compatible with photothermal decomposition [220][221][222]. In the case of polystyrene irradiated at 193 nm, an adiabatic expansion model inferred temperatures of 2,350 K [223]. When absorbing chromophores were purposefully added to PMMA, a combined photochemical/photothermal mechanism was evident [224].…”

Section: Introductionmentioning

confidence: 98%

Laser Application of Polymers

Lippert

2004

Polymers and Light

148

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Laser ablation of polymers has been studied with designed materials to evaluate the mechanism of ablation and the role of photochemically active groups on the ablation process, and to test possible applications of laser ablation and designed polymers. The incorporation of photochemically active groups lowers the threshold of ablation and allows high-quality structuring without contamination and modification of the remaining surface. The decomposition of the active chromophore takes place during the excitation pulse of the laser and gaseous products are ejected with supersonic velocity. Time-of-flight mass spectrometry reveals that a metastable species is among the products, suggesting that excited electronic states are involved in the ablation process. Experiments with a reference material, i.e., polyimide, for which a photothermal ablation mechanism has been suggested, exhibited pronounced differences. These results strongly suggest that, in case of designed polymers which contain photochemically active groups, a photochemical part in the ablation mechanism cannot be neglected. Various potential applications for laser ablation and the special photopolymers were evaluated and it became clear that the potential of laser ablation and specially designed material is in the field of microstructuring. Laser ablation can be used to fabricate three-dimensional elements, e.g., microoptical elements.Keywords Laser ablation · Ablation mechanism · Photopolymers · Polyimide · Spectroscopy This was not always true, of course. For many years, the laser was viewed as "an answer in search of a question". That is, it was seen as an elegant device, but one with no real useful application outside of fundamental scientific research. In the last two to three decades however, numerous laser applications have moved from the laboratory to the industrial workplace or the commercial market. Lasers are unique energy sources characterized by their spectral purity, spatial and temporal coherence, and high average peak intensity. Each of these characteristics has led to applications that take advantage of these qualities: -Spatial coherence: e.g., remote sensing, range finding and many holographic techniques. -Spectral purity: e.g., atmospheric monitoring based on high-resolution spectroscopies. -and of course the many other applications in communication and storage, e.g., CDs.All of these high-tech applications have come to define everyday life in the late twentieth century. One property of lasers, however, that of high intensity, did not immediately lead to "delicate" applications but rather to those requiring "brute force". That is, the laser was used in applications for removing material or heating. The first realistic applications involved cutting, drilling, and welding, and the laser was little more advanced than a saw, a drill, or a torch. In a humorous vein A.L. Schawlow proposed and demonstrated the first "laser eraser" in 1965 [4], using the different absorptivities of paper and ink to remove the ink without damaging the und...

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“…For several polymers such as polystyrene, Teflon, and polymethyl methacrylate ͑PMMA͒, Maxwell-Boltzmann distributions were obtained, yielding temperatures compatible with photo-thermal decomposition. [11][12][13] In the case of polystyrene irradiated at 193 nm, an adiabatic expansion model inferred temperatures of ϳ2350 K. 14 When absorbing chromophores were purposefully added to PMMA, a combined photochemical/photothermal mechanism was evident. 15 In general, most TOF-mass spectrometer ͑MS͒ studies have given strong indications for photothermal ablation mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Analysis of neutral fragments from ultraviolet laser irradiation of a photolabile triazeno polymer

Lippert

Langford

Wokaun

et al. 1999

Journal of Applied Physics

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Articles you may be interested inNovel two-step laser ablation and ionization mass spectrometry (2S-LAIMS) of actor-spectator ice layers: Probing chemical composition of D2O ice beneath a H2O ice layer Dependence of ultraviolet nanosecond laser polymer ablation on polymer molecular weight: Poly(methyl methacrylate) at 248 nm A photolabile triazeno polymer was irradiated with pulsed excimer laser light at 248 nm and 30 ns pulse width. The ablation fragments were analyzed using time-of-flight ͑TOF͒ mass spectrometry. At fluences below 1.3 J/cm 2 , only neutral products were found. At these fluences, N 2 is by far the most intense neutral signal along with measurable phenyl radical ͑mass 76͒ production. The N 2 TOF shows a fast shoulder corresponding to kinetic energies of about 1.1 eV and a long slow tail persisting for hundreds of microseconds. The tail is attributed to delayed emission of reaction products from the polymer. The kinetic energy of the fast peak is attributed to direct ejection of products from surface sites undergoing exothermic decomposition. A weaker signal due to the phenyl radical is also observed. The observed fluence dependence of the two major products is highly nonlinear and is shown to fit an Arrhenius equation. We discuss the implications of these measurements regarding photochemical versus photothermal processes.

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Mass spectroscopic studies of the ArF-laser photoablation of polystyrene

Cited by 73 publications

References 13 publications

Photochemical Interaction of Polystyrene Nanospheres with 193 nm Pulsed Laser Light

Photochemical Interaction of Polystyrene Nanospheres with 193 nm Pulsed Laser Light

Laser Application of Polymers

Analysis of neutral fragments from ultraviolet laser irradiation of a photolabile triazeno polymer

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