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--- howto:t3r_antibunching_-_slow_decay [2015/06/03 15:06] – admin
+++ howto:t3r_antibunching_-_slow_decay [2022/02/01 10:54] – [A.: The decay can be caused by blinking of the nanodiamonds.] peter
@@ Line 1: / Line 1: @@
-====== T3R Antibunching - Slow Decay ======
+{{tag> antibunching T3-mode T2-mode}}
+~~TOC~~
+====== Artefacts in Antibunching Histograms - Slow Decay ======
-===== Q.: How can we avoid decay at very long time delay (up to 5us)? =====
-==== In this show-case the external preconditions are: ====
-- detectors: perkin elmer SPCMAQR14
-- 700 nm SP filter in front of one of the APDs
-- sample: diamond nanocrystals (100 nm), we are measuring the antibunching of the NV centers emission
-- laser wavelength: 532 nm, cw
-- T3R Measurement with PicoHarp Software
-===== A.: The decay can be caused by blinking of the nanodiamonds. =====
 ==== A decay caused by correlation statistics ====
+This decay is caused by correlation statistics. This happens because you correlate the first arriving photon against a photon at the longer time, which will be an increasingly unlikely event because the earliest stop photons always win and the experiment restarts.
-On top of an eventual blinking you will have a decay caused by correlation statistics.
-This happens because you correlate the first arriving photon against a photon at the longer time,
-which will be an increasingly unlikely event because the earliest stop photons always win and the experiment restarts.
 I attached a simulation.
@@ Line 30: / Line 16: @@
-\\ ==== You will I need the raw data ====
+\\
 The timescale is in ns. The plateau is the [[glossary:dead time]]. The decay slope depends on the count rate.
-You can zoom into your data and you will see roughly the same behavior - linear decay after the [[glossary:dead time]], which than of course is overshadowed by the background.
+The way to avoid this is to calculate the total correlation after T2 MODE MEASUREMENT. This is not a start-stop correlation but the correlation of every photon against every photon.
-The way to avoid this is is to calculate the total correlation. This is not a start-stop correlation but the correlation of every photon against every photon.
-It can be done measuring in T2 mode and then correlating using the SymPhoTime Software (http://www.picoquant.com/products/sw_mt/sw_mt.htm).
-For a trial you will I need the raw data - a pt2 file containing all the photon data - not just the correlated curve. You can record this using the button I highlighted in the attached screenshot.
+It can be done using the SymPhoTime Software (http://www.picoquant.com/products/sw_mt/sw_mt.htm).