Use of monoatomic and polyatomic projectiles for the characterisation of polylactic acid by static secondary ion mass spectrometry

Abstract

The application of polyatomic primary ions is a strongly developing branch of static secondary ion mass spectrometry (S-SIMS), since these projectiles allow a significant increase in the secondary ion yields to be achieved. However, the different limitations and possibilities of certain polyatomic primary ions for use on specific functional classes of samples are still not completely known. This paper compares the use of monoatomic and polyatomic primary ions in S-SIMS for thin layers of polylactic acid (PLA), obtained by spin-coating solutions on silicon wafers. Bombardment with Ga+, Xe+ and SF5+ primary ions allowed the contribution of the projectile mass and number of atoms in the gain in ion yield and molecular specificity (relative importance of high m/z and low m/z signals) to be assessed. Samples obtained by spin-coating solutions with increasing concentration showed that optimal layer thickness depended on the primary ion used. In comparison with the use of Ga+ projectiles, the yield of structural ions increased by a factor of about 1.5 to 2 and by about 7 to 12 when Xe+ and SF5+ primary ion bombardment were applied, respectively. A detailed fragmentation pattern was elaborated to interpret ion signal intensity changes for different projectiles in terms of energy deposition and collective processes in the subsurface, and the internal energy of radical and even-electron precursor ions.

Comparison of primary monoatomic with primary polyatomic ions for the characterisation of polyesters with static secondary ion mass spectrometry

“…Although the solubility of the polyesters in organic solvents with sufficient volatility for spincoating limits the preparation of thick multilayers, the trends seen for the polyesters studied contrast with data on e.g. polylactide and polymethylmethacrylate 30, 31. Specifically, both polymers show a clear maximum in the plots of the secondary ion intensity as a function of the concentration of the spincoated solution.…”

Cluster secondary ion mass spectrometry of polymers and related materials

“…Some examples include work by Davies et al (2003), who found enhancement in signals characteristic of PET and polypeptides when employing Au þ 3 clusters, Nagy and Walker who observed similar enhancements using Au (Nagy, Gelb, & Walker, 2005) and Bi (Nagy & Walker, 2007) clusters for bombardment of polystyrene and other organic materials, and several others [Au clusters (Bryan et al, 2004;Aimoto et al, 2006;Zhu & Kelley, 2006), C 60 Hill & Blenkinsopp, 2004), SF þ 5 (Gillen & Roberson, 1998;Stapel, Thiemann, & Benninghoven, 2000;Stapel & Benninghoven, 2001;Boschmans, Van Royan, & Van Vaeck, 2005;Van Royen, Taranu, & Van Vaeck, 2005)]. …”

A Simple Method for Quantification of Polyhydroxybutyrate and Polylactic Acid Micro-Bioplastics in Soils by Evolved Gas Analysis

“…The results show that, although these m / z are specific to PLA and would be useful for samples containing higher amounts of organic matter, the signal at m / z 100 and 128 was not intense enough for the analysis of real samples ( Figure 8 ). Although the signal at m / z 56 ( Figure 9 ) from the PLA dimer was more intense, there was signal splitting, and the main peak was not separated from the other two peaks [ 67 ]. The last peak ended at a temperature higher than 550 °C, which increased the analysis time and was instrumentally more demanding.…”