Zeiss LSM 880 Operating Manual page 209

LSM 880
C. Bunching terms
Bunching is the phenomenon of a burst of photons during a certain time interval, the duration of which
is determined by photo-physical processes including triplet, blinking, flickering and protonation. These
terms are exponential decay functions. Formally, they look the same, only the exponential decay might be
different.
C.1 Triplet
t
−
t
t
= − + ⋅
G ( ) 1 ( T T e
t t t
t
−
t
⋅
T e
t
t
= +
t
G ( ) 1 ( )
t
−
1 T
t
is the triplet fraction, that is the number of molecules undergoing triplet states and t
where T
t
decay time.
and t
T are fitted parameters.
t t
Triplet is based on an un-allowed intersystem crossing from the excited to the so-called triplet state. This
state lasts for 1 – 5 µs. If the electron drops back to the ground state, no photon is emitted and hence
during the triplet state the molecule is in a dark state. Triplet is indicated as a rise in the correlation
amplitude, which is indicated as a deviation from the flattening curve at shorter correlation times. If not
normalized, the triplet fraction contributes to the total number of molecules.
C.2 Blinking
t
−
t
t
= − +
G ( ) 1 ( T T e b
b b b
t
−
t
⋅
T e
b
t
= +
b
G ( ) 1 ( )
b −
1 T
b
is the blinking fraction, that is the number of molecules in the dimmer state and t
where T
b
decay time of the dimmer state. Note, if the blinking term is not normalized, the number of blinking
molecules will influence the total number of molecules.
and t
T are fitted parameters.
b b
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CHAPTER 1 - SYSTEM OPERATION
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not normalized
t )
normalized
not normalized
)
normalized
000000-2071-464
ZEISS
(7a)
(7b)
the triplet
t
(7c)
(7d)
the blinking
b
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