José Manuel Riveros Nigra, Paraguayan-born Brazilian physical chemist (Asunción 16 April 1940 –

Performed important contributions to ion-molecule reactions in gas phase

Described Riveros reaction or α-elimination of CO leading to the carbonylation of the esther, an efficient way of generating  a solvated ion in the gas phase at low pressures (1968)

With S.M. José & K. Takashima. A novel reaction to generate anion adducts in the gas phase (1989)

With P. C. Isolani, H.V. Linnert, M.C. Kida-Tinone et al. Construção e desempenho de um espectrômetro de massa por transformada de Fourier. Quim. Nova 15:351-3, 1992

With Z. Zhu. A kinetic method to distinguish isomeric C₃H₅⁺ cations. Rapid Comm.Mass. Spectrom. 5:387-90, 1991