6"
"
some"of"the"Varian"accessories."You"can"collect"a"baseline"immediately"before"
scanning"a"sample"or"use"a"stored"baseline."
The"accuracy"of"your"baseline"determines"the"accuracy"of"your"measurement.""
You"should"perform"a"zero/baseline"correction"before"running"your"samples"
after"the"instrument"has"warmed"up"for"~20"minutes"using"the"same"scan"
parameters"that"you"will"use"for"your"sample.""
The"Cary"WinUV"system"collects"a"new"baseline"when"you"select"any"type"of"
baseline"correction"in"the"Baseline"tab"of"the"Setup"dialog"box"and"then"click"
Baseline"button"in"the"application"window."Depending"on"the"type"of"correction"
you"have"selected,"the"Cary"will"prompt"you"to"perform"either"one"or"two"
baseline"scans."The"first"is"a"100%Tbaseline"(for"the"DRA"with"the"100%"
reference"material"in"the"sample"positions)."The"second,"if"required,"is"a"
0%Tbaseline"(with"the"sample"beam"blocked)."
Once"the"baselines"have"been"collected,"they"will"be"automatically"applied"to"
each"collected"sample"data"point"as"it"is"displayed"(indicated"by"the"red"display)."
If"there"is"not"a"corresponding"data"point"in"the"current"baseline,"then"the"file"
will"be"interpolated"to"provide"the"correction."The"correction"applied"to"each"
point"is"dependent"on"the"selected"baseline"type"in"the"Baseline"tab.""
A"baseline"cannot"be"applied"to"a"sample"where"the"abscissa"range"of"the"sample"
exceeds"that"of"the"baseline."If"you"change"your"abscissa"range"to"one"outside"
that"of"the"baseline,"the"Cary"will"display"an"error"message."Also"the"red"text"in"
the"ordinate"display"which"indicates"that"baseline"correction"mode"is"activated"
will"disappear."
For"reflection"measurements"using"the"aperture"kit,"if"the"beam"spot"overfills"the"
aperture,"you"can"correct"for"this"“stray"light”"by"performing"a"Zero/baseline"
Correction.""Normally,"the"0%TBaseline"scan"is"run"by"blocking"the"beam"before"
it"enters"the"integrating"sphere,"which"accounts"for"electronic"noise."In"this"case,"
do"not"block"the"beam,"but"instead"remove"the"reflectance"port"cap"to"account"
for"the"light"reflecting"on"the"edges"of"the"aperture"(the"remainder"of"the"light"
should"pass"through"the"integrating"sphere"and"not"be"detected)."""
Performing&a&Zero/Baseline&Correction:"Select"this"option"to"apply"a"100%T"
baseline"correction"(100%TBaseline)"and"a"zero-line"correction"(0%TBaseline)"
to"the"sample"scan"(S)."This"correction"is"performed"with"the"raw"transmission"
data"and"is"thus:"
(𝑆−(0%𝑇𝐵𝑎𝑠𝑒𝑙𝑖𝑛𝑒))
(100%𝑇𝐵𝑎𝑠𝑒𝑙𝑖𝑛𝑒 −0%𝑇𝐵𝑎𝑠𝑒𝑙𝑖𝑛𝑒)"
With"this"option,"the"Cary"will"prompt"you"to"perform"a"100%TBaseline"first,"
followed"by"a"0%TBaseline"when"you"perform"a"baseline"collection."
This"baseline"option"corrects"for"any"inherent"variations"in"the"electronic"zero"
line"of"the"instrument."You"should"use"this"baseline"option"if"your"samples"have"
areas"of"very"low"transmission"(high"absorbance)"as"any"variations"in"the"
