Spectroscopic studies of ArF laser photoablation of PMMA

Davis, G. M.; Gower, Malcolm C.; Fotakis, C.; Efthimiopoulos, T.; Argyrakis, P.

doi:10.1007/bf00616456

Cited by 86 publications

(28 citation statements)

References 9 publications

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“…We also assume no fragmentation during ionization. The velocities calculated in the present work are an order of magnitude smaller than those of CN (6.5 x l0 s cm/s) in the ablation of polyimide at 248 nm [19] and CH, C2, and CN ( 2 -5 x 105 cm/s) in the ablation of PMMA at 193 nm [22]. For the 1064 nm ablation, the change in the intensities also depend on the delay time of ionization.…”

Section: Resultsmentioning

confidence: 60%

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: 60%

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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“…Furthermore, the exact value of T a (0) is unknown, and must be estimated (typical estimates for ablation temperatures are T a (0) ∼ 10 4 K [46]). Nonetheless, we expect that Eq.…”

Section: Thermalizationmentioning

confidence: 99%

A bright, slow cryogenic molecular beam source for free radicals

Barry

Shuman

DeMille

2011

Phys. Chem. Chem. Phys.

165

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We demonstrate and characterize a cryogenic buffer gas-cooled molecular beam source capable of producing bright beams of free radicals and refractory species. Details of the beam properties (brightness, forward velocity distribution, transverse velocity spread, rotational and vibrational temperatures) are measured under varying conditions for the molecular species SrF. Under typical conditions we produce a beam of brightness 1.2×10 11 molecules/sr/pulse in the X 2 Σ + (v = 0, Nrot = 0) state, with 140 m s forward velocity and a rotational temperature of ≈ 1 K. This source compares favorably to other methods for producing beams of free radicals and refractory species for many types of experiments. We provide details of construction that may be helpful for others attempting to use this method.

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“…Time-resolved emission spectroscopy can give information about the composition [21][22][23] and the temperatures inside the plasma, which is formed at high irradiation fluences.…”

Section: Introductionmentioning

confidence: 99%

Time-resolved techniques as probes for the laser ablation process

Hauer

Funk

Lippert

et al. 2005

Optics and Lasers in Engineering

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Laser material processing is an increasing market although many processes are still not yet fully understood. It was repeatedly emphasized that a better understanding of the transient processes can help to improve the understanding of the ablation mechanism. Examples using ns-surface interferometry, ns-shadowgraphy and emission spectroscopy are shown to illustrate how these techniques can be used to obtain new insights in the laser ablation processes.Time-resolved surface interferometry probes the remaining polymer, while ns-shadowgraphy and plasma spectroscopy observe the ablation products. Ns-shadowgraphy can be used for fluences just above the ablation threshold, to the fluences where a plasma is observed, which is probed by emission spectroscopy.Time-resolved ns-surface interferometry of a specially designed triazene polymer reveals that the surface morphology changes and thereby the surface removal occurs only during the laser pulse. Ns-shadowgraphy is used to observe the shockwave and the plume of fragments, which are generated during laser ablation. A comparison of the ablation properties of an energetic polymer at two different wavelengths (1064 and 193 nm) shows that the ejection of non-gaseous fragments (solid or liquid) is only detected after irradiation with 1064 nm. At higher laser fluences, plasma is formed, and the atomic (H), and diatomic species (CN, CH and C 2 ) are identified. r

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Spectroscopic studies of ArF laser photoablation of PMMA

Cited by 86 publications

References 9 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

A bright, slow cryogenic molecular beam source for free radicals

Time-resolved techniques as probes for the laser ablation process

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