Table 1. Molecular Weights Associated With Different Compounds Detected by PTR-MS		
m/z (mass + 1)	Structure	Description
Primary signal		
  21	H218OH+	isotope of primary ion
  37	H2OH2OH+	primary ion water cluster
Cyclohexanea		
  39, 40, 41, 43, 44, 53, 56, 57, 58, 69, 83, 84, 85, 86		cyclohexane
  99, 100	C6H10OH+	cyclohexane + OH oxidation product
Oxidation products from all ozonlysis experiments		
  31	CH2OH+	formaldehyde
  45	C2H4OH+	acetaldehyde
  47	CH2O2H+	formic acid
  59	C3H6OH+	acetone
  61	C2H4O2H+	acetic acid
3-carene		
  81, 82, 137, 138b	C10H16H+, C6H9H+	monoterpene, fragments and isotopes
  71, 73, 87, 89, 97, 107, 111*,c 113*, 115, 123*, 125, 127, 141*, 151, 167, 169d		unidentified oxidation products
alpha-terpinene		
  81, 82, 137, 138	C10H16H+, C6H9H+	monoterpene, fragments and isotopes
  73, 87, 89, 107, 109, 113*, 115, 123*, 125, 127, 139, 141*, 143, 151, 155*, 157, 167, 171, 183, 185, 201		unidentified oxidation products
beta-caryophyllene		
  67, 68, 81, 82, 95, 109, 121, 137, 149, 205, 206	C15H24H+	sesquiterpene, fragments, and isotopes
  71, 73, 87, 115, 127, 133, 139, 151, 153, 159*, 177, 197, 219, 223, 237, 253		unidentified oxidation products
alpha-humulene		
  67, 81, 82, 95, 96, 97, 103, 109, 110, 121, 123, 135, 137, 149, 150, 205, 206,	C15H24H+	sesquiterpene, fragments, and isotopes
  71, 73, 115, 125, 127, 129, 141*, 197, 219, 221		unidentified oxidation products
alpha-pinene		
  81, 82, 137, 138	C10H16H+, C6H9H+	monoterpene, fragments and isotopes
  71, 72, 107, 108, 123*, 151, 152, 169, 170	C10H16O2H+	uncalibrated oxidation product: pinonaldehyde, fragments, and isotopese
  73, 75, 79, 87, 97, 111*, 113*, 115, 117, 125, 127, 129, 133, 139, 141*, 143, 147, 155*, 165, 167, 171, 183, 185		unidentified oxidation products
Terpinolene		
  81, 82, 137, 138	C10H16H+, C6H9H+	monoterpene, fragments and isotopes
  71, 73, 87, 93, 109, 111*, 113*, 115, 125, 127, 129, 141*, 143, 157, 167		unidentified oxidation products
beta-pinene		
  81, 82, 137, 138	C10H16H+, C6H9H+	monoterpene, fragments and isotopes
  97, 103, 121, 122, 139, 140, 141*	C9H14OH+, C9H12H+	calibrated oxidation product: nopinone, isotopes and fragments
  107, 109, 111*, 113, 119, 123*, 125, 129, 153, 155*, 169*, 171, 185		unidentified oxidation products
Myrcene		
  81, 82, 137, 138	C10H16H+, C6H9H+	monoterpene, fragments and isotopes
  71, 73, 75, 79, 93, 97, 111*, 113*, 115, 127, 139		unidentified oxidation products
Methyl chavicol		
  149, 150	C10H12OH+	oxygenated terpene and isotope
  109, 115, 121,125, 137, 151*, 152, 163		unidentified oxidation products
Linalool		
  81, 82, 137, 138, 155, 156	C10H18OH+, C10H16H+	oxygenated terpene, fragments, and isotopes
  73, 75, 93, 94, 111*, 113*, 115, 127, 128, 129, 130		unidentified oxidation products
aMasses associated with cyclohexane listed in bold font were >10% of the parent ion m/z 85.		
bAll monoterpenes occur predominantly on the parent m/z 137 and the fragment m/z 81 ions, with a small fraction (<20%) occurring on the 13C isotope with m/z (138, 82).		
cAsterisks following unidentified oxidation products represent unidentified ions that were observed in the canopy air of a coniferous forest in California by PTR-MS [Holzinger et al., 2005].
dUnidentified oxidation products in bold font represent ions with >5% yield (on a mole basis) from the parent terpene.
eFragments were determined from correlations with m/z 151 (the dominant pinonaldehyde ion), and agreed well with fragmentation patterns reported elsewhere for pinonaldehyde [Wisthaler et al., 2001].