Atomic and nuclear properties of materials:
Air (dry, 1 atm)

Quantity	Value	Units	Value	Units
<Z/A>	0.49919
Specific gravity (20° C, 1 atm)	1.20E-03	g cm-3
Minimum ionization	1.815	MeV g-1cm2	2.187E-03	MeV cm-1
Nuclear collision length	61.3	g cm-2	5.088E+04	cm
Nuclear interaction length	90.1	g cm-2	7.477E+04	cm
Pion collision length	88.5	g cm-2	7.348E+04	cm
Pion interaction length	122.0	g cm-2	1.013E+05	cm
Radiation length	36.62	g cm-2	3.039E+04	cm
Critical energy	87.92	MeV (for e-)	85.96	MeV (for e+)
Molière radius	8.83	g cm-2	7330.	cm
Plasma energy	0.71	eV
Muon critical energy	1115.	GeV
Boiling point @ 1 atm	78.80	K	-194.4	C
Index of refraction (@ STP, Na D)	172.	(n-1)x106

Composition:

Elem	Z	Atomic frac*	Mass frac*
C	6	0.00	0.000124
N	7	0.00	0.755267
O	8	0.00	0.231781
Ar	18	0.00	0.012827
* calculated from mass fraction data.

Explanation of some entries
For muons, dE/dx = a(E) + b(E) E. Tables of b(E): PS PDF TEXT
Table of muon dE/dx and Range: PS PDF TEXT