In a famous paper published in 1982, a very special class of gunshot residue particles(GSR) was named by Samarendra Basu "peeled orange", due to their particular structure, consisting of a barium/antimony co...In a famous paper published in 1982, a very special class of gunshot residue particles(GSR) was named by Samarendra Basu "peeled orange", due to their particular structure, consisting of a barium/antimony core covered by an outer lead leaflet. In this class of GSR particles the surface may show nodular structures of lead. Basu proposed an explanation in terms of a nucleus of antimony and barium that captures lead vapours produced after the explosion of a cartridge into a firearm: as solidification points of antimony and barium are close one another, both higher than solidification point of lead, he stated that lead occurs as a layer around the core in peeled orange GSR particles. In this paper we study the thermodynamic of the barium/antimony alloy and we hypothesize a formation process in terms of colloidal metal growth, charged particles and electrostatic attraction. We propose an updated model of formation for peeled orange GSR particles that explains the existence of outer lead leaflet and nodules in terms of electrostatic attraction of lead nanoparticles and instability of lead droplets.展开更多
文摘In a famous paper published in 1982, a very special class of gunshot residue particles(GSR) was named by Samarendra Basu "peeled orange", due to their particular structure, consisting of a barium/antimony core covered by an outer lead leaflet. In this class of GSR particles the surface may show nodular structures of lead. Basu proposed an explanation in terms of a nucleus of antimony and barium that captures lead vapours produced after the explosion of a cartridge into a firearm: as solidification points of antimony and barium are close one another, both higher than solidification point of lead, he stated that lead occurs as a layer around the core in peeled orange GSR particles. In this paper we study the thermodynamic of the barium/antimony alloy and we hypothesize a formation process in terms of colloidal metal growth, charged particles and electrostatic attraction. We propose an updated model of formation for peeled orange GSR particles that explains the existence of outer lead leaflet and nodules in terms of electrostatic attraction of lead nanoparticles and instability of lead droplets.
