Zeiss LSM 880, Operating Manual

Page: 216 / 690

CHAPTER 1 - SYSTEM OPERATION
ZEISS Left Tool Area and Hardware Control Tools LSM 880
210 000000-2071-464 10/2014 V_01
t
d,i
are fitted parameters. They can be converted to diffusion coefficients D
i
using formulas 5e or 5f. The
FCS software allows you to directly fit to D
i
values, but in this case the lateral radius
ω
r
has to be specified
as a fixed value.
Please note that in the case of anomalous diffusion the following relations exist:
i
r
i d
, 2
2
,
Γ
=
ω
t
α
1 photon excitation (8h)
i
r
i d
, 2
2
,
2
Γ ⋅
=
ω
t
α
2 photon excitation
(8i)
with
Γ
representing the transport coefficient of the fractional time dimension.
Please note the following relation between D and G:
1
) (
−
⋅ Γ =
α
t t D
(8j)
If activating the fitting to the diffusion coefficient in the FCS the
Γ
values have to be calculated from the
D values by the following conversion:
D
⋅ = Γ
4
(8k)
The
Φ
i
values are fit parameters. They account for different brightness of different components. In
principle, if molecules of different brightness are present, the apparent molecular brightness is defined as
∑
∑
=
=
⋅
⋅
=
3
1
3
1
2
i
i i
i
i i
f
f
η
η
η
(8l)
with
η
i
being the brightness of the molecules in kHz or the dimensionless relative brightness values. The
brightness of the species has to be determined beforehand in control experiments.