Absorption cross-sections for C5 hydroperoxy-aldehydes (C5HPALD1 and C5HPALD1) formed from isoprene are assumed equivalent to those of methcrolein. Methacrolein CH2C(CH3)CHO absorption cross-sections (298K) Taken from: MPI_Mainz Spectral Atlas (http://www.atmosphere.mpg.de/enid/2295) IUPAC 2005 Recommendation http://www.iupac-kinetic.ch.cam.ac.uk T. Gierczak, J.B. Burkholder, R.K. Talukdar, A. Mellouki, S.B. Barone, and A.R. Ravishankara: Atmospheric fate of methyl vinyl ketone and methacrolein, J. Photochem. Photobiol. A: Chem. 110, 1-10 (1997) Quantum Yields A value of QY = 1.0 is assumed over the relevant wavelength range, based on information provided by Peeters and co-workers: Peeters et al., HOx radical regeneration in the oxidation of isoprene: Phys. Chem. Chem. Phys., 28, 5935–5939 (2009). T = 298 K, resolution = 1 nm wavelength (nm) xsect (cm2) 250 2.07E-21 251 1.94E-21 252 1.87E-21 253 1.80E-21 254 1.78E-21 255 1.77E-21 256 1.80E-21 257 1.80E-21 258 1.86E-21 259 1.93E-21 260 2.01E-21 261 2.11E-21 262 2.24E-21 263 2.41E-21 264 2.63E-21 265 2.83E-21 266 3.05E-21 267 3.33E-21 268 3.63E-21 269 3.98E-21 270 4.36E-21 271 4.79E-21 272 5.20E-21 273 5.67E-21 274 6.16E-21 275 6.73E-21 276 7.32E-21 277 7.93E-21 278 8.63E-21 279 9.36E-21 280 1.01E-20 281 1.09E-20 282 1.18E-20 283 1.26E-20 284 1.35E-20 285 1.45E-20 286 1.56E-20 287 1.67E-20 288 1.79E-20 289 1.90E-20 290 2.03E-20 291 2.16E-20 292 2.28E-20 293 2.40E-20 294 2.52E-20 295 2.68E-20 296 2.85E-20 297 2.99E-20 298 3.13E-20 299 3.26E-20 300 3.44E-20 301 3.61E-20 302 3.76E-20 303 3.91E-20 304 4.04E-20 305 4.19E-20 306 4.40E-20 307 4.58E-20 308 4.71E-20 309 4.81E-20 310 4.92E-20 311 5.13E-20 312 5.35E-20 313 5.50E-20 314 5.61E-20 315 5.70E-20 316 5.87E-20 317 6.04E-20 318 6.19E-20 319 6.28E-20 320 6.27E-20 321 6.18E-20 322 6.21E-20 323 6.34E-20 324 6.58E-20 325 6.74E-20 326 6.73E-20 327 6.68E-20 328 6.83E-20 329 7.07E-20 330 7.15E-20 331 7.16E-20 332 7.03E-20 333 6.69E-20 334 6.41E-20 335 6.08E-20 336 5.97E-20 337 6.25E-20 338 6.38E-20 339 6.37E-20 340 6.24E-20 341 6.02E-20 342 5.98E-20 343 6.58E-20 344 6.79E-20 345 6.53E-20 346 6.11E-20 347 5.63E-20 348 5.22E-20 349 4.55E-20 350 4.16E-20 351 3.85E-20 352 3.89E-20 353 4.35E-20 354 4.31E-20 355 4.14E-20 356 3.62E-20 357 3.53E-20 358 3.46E-20 359 3.81E-20 360 5.05E-20 361 4.28E-20 362 3.61E-20 363 2.86E-20 364 2.68E-20 365 2.33E-20 366 1.92E-20 367 1.62E-20 368 1.40E-20 369 1.31E-20 370 1.42E-20 371 1.67E-20 372 1.53E-20 373 1.43E-20 374 1.08E-20 375 9.77E-21 376 1.00E-20 377 1.07E-20 378 1.35E-20 379 2.18E-20 380 1.30E-20 381 9.84E-21 382 5.55E-21 383 4.56E-21 384 3.64E-21 385 3.31E-21 386 2.46E-21 387 2.05E-21 388 1.81E-21 389 1.61E-21 390 1.47E-21 391 1.56E-21 392 1.59E-21 393 1.53E-21 394 1.49E-21 395 1.23E-21