iDirac: a field-portable instrument for long-term autonomous measurements of isoprene and selected VOCs. - Bolas, Conor G.; Ferracci, Valerio; Robinson, Andrew D.; Mead, Mohammed I.; Nadzir, Mohd Shahrul Mohd; Pyle, John A.; Jones, Roderic L.; Harris, Neil R. P. (Atmospheric Measurement Techniques, 2020)