Table 2:

Quantities relevant to PAH survival.

	(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)
component					x	z0/H
	eV	10-4 Å2							m/s
photosphere	2.7	700	1	1.2	-	4.4	0.5	5 s	-
FUV	4.2	700	1	1.5	-	4.5	0.5	120 s	-
EUV	97	36	0.5	110	9	5.3	0.4	9 days	2900
X-ray	1100	0.17	1	0.55	100	4.2	0.5	290 yr	3.4

Notes.  and refer to r=10 AU.
(1) The mean energy of destructive photons from Eq. (5) at the bottom of the extinction layer (see Fig. 5); for photospheric and FUV photons we put and for EUV and X-rays we integrate for (Eq. (10)); (2) absorption cross section per C atom at a frequency ; (3) approximate mean degree of ionization of the gas in the extinction layer ; (4) extinction cross section of gas and dust at frequency normalized to  cm² g^-1; (5) number of expelled atoms x per absorption event from Eq. (14); (6) altitude of the bottom of the extinction layer in units of the scale height H; (7) thickness of extinction layer; (8) mean time from Eq. (4) in which one photon is absorbed; (9) critical vertical velocity for PAH survival.