Laser interference ablation

Direct Laser Interference Micro-Nanopatteming (DLIP) has been used to build nanometer sized PANI arrays (as thin as 600 nm) self-assembled on dielectric polymers the width of the polymer lines can be modulated by changing the laser beam intensity, without loss of the chemical and electronic properties of PANI. It is interesting that the dielectric substrate can be ablated, exploiting its optical properties at the working wavelength. The authors believe this technique relevant for the development of polymer based sensors [170]. 

ICP-OES is a destructive technique that provides only elemental composition. However, ICP-OES is relatively insensitive to sample matrix interference effects. Interference effects in ICP-OES are generally less severe than in GFAA, FAA, or ICPMS. Matrix effects are less severe when using the combination of laser ablation and ICP-OES than when a laser microprobe is used for both ablation and excitation. 

Laser microprobe MS (LMMS) can be used for direct analysis of normal-phase HPTLC plates [802,837]. Kubis et al. [802] used polyamide TLC plates polyamide does not interfere with compound identification by the mass spectrum, owing to its low-mass fragment-ions (m/z < 150). LMMS is essentially a surface analysis technique, in which the sample is ablated using a Nd-YAG laser. The UV irradiation desorbs and ionises a microvolume of the sample the positive and negative ions can be analysed by using a ToF mass spectrometer. The main characteristics of TLC-LMMS are indicated in Table 7.84 [838],... 

Jackson SE, Gunther D (2003) The nature and sources of laser induced isotopic fractionation in laser ablation-multicollector-inductively coupled plasma-mass spectrometry. J Anal At Spectrom 18 205-212 Jiang S-J, Houk RS, Stevens MA (1988) Alleviation of overlap interferences for determination of potassium isotope ratios by Inductively-Coupled Plasma Mass Spectrometry. Anal Chem 60 1217-1220 Lam JWH, Horlick G (1990) A comparison of argon and mixed gas plasmas for inductively coupled plasma-mass spectrometry. Spectrochim Acta Part B 45 1313-1325 Langmuir I, Kingdon KH(1925) Thermionic effects caused by vapours of alkali metals. Phil Trans R Soc A107 61-79... 

ICP-AES was validated for the simultaneous determination of Al, B, Ba, Be, Cd, Co, Cr, Cu, Fe, Li, Mn, Ni, Pb, Se, Sr and Zn in human serum in a clinical laboratory. The samples underwent digestion and yttrium was used as an internal standard. The LOD were as follows 0.002-0.003 (xM for Ba, Cd, Mn and Sr 0.014-0.07 (xM for Be, Co, Cr, Cu, Fe, Li, Ni, Pb and Zn and 0.2-0.9 (xM for Al, B and Se. The concentrations of Al, Be and Co in human serum were found to be above the LOD, while those of Cd, Cr, Ni and Pb were below the LOQ however, in case of acute intoxication with the latter elements the method is valid . Matrix effects were evaluated for ICP-AES analysis using solution nebulization and laser ablation (LA) techniques. The main matrix-related interferences stem from elements with a low second ionization potential however, these are drastically reduced when pure He is used as carrier gas. This points to Ar (the usual carrier) participation in the interference mechanism, probably by interacting with doubly charged species. ... 

In inductively coupled plasma-mass spectrometry, isobaric interference occurs between species with the same mass and charge. Interference can be eliminated if the mass spectral resolution is sufficiently great or by dissociating an interfering polyatomic species with a collision cell. When laser ablation is used to sample a solid, matrix-matched standards are often necessary for quantitative analysis. 

Thermal ablation. The SRG is normally 7t-shifted in relation to the interference pattern, and is the result of the application of a very intense pulse of laser light or a high-power continuous wave (cw) laser. The SRGs cannot be optically erased, but rather only thermally erased. In some experiments, some polarization dependence was observed, which cannot be explained with present knowledge of the field. The dye does not need to be azobenzene for such SRGs (see Grzybowski et... 

In order to produce surface-relief electro-optic gratings, Munakata et compared two fabrication methods of SRG inscription. In the first, the SRG was produced with an interference pattern of cw laser, with relatively modest intensities. The gratings so recorded were photo- and thermally erasable, and efficient writing was polarization dependent. In the second method, a phase mask was employed to provide the periodic intensity modulation of a pulsed laser, the 3rd-order harmonic (at 355 nm) of a Nd YAG laser. The SRG was produced with a single laser pulse, allowing a very short fabrication time (less than Is). The direshold for ablation was 500 mj/(em pulse), and the amplitude of the SRG increased with pulse energy. A depth of up to 300 rim could be achieved, leading to a smooth but not sinusoidal surface modulation. 

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