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7/23/2019 Laser Diffraction (1)

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LASER DIFFRACTION

JESSICA D’SOUZA

TANAYA BANSOD



WHAT IS DIFFRACTION?



PRINCIPLE OF LASERDIFFRACTION

•

Measures the angularvariation ! intensity "#$%ht s&attere'

• Ca$&u$ates size "# the

(art&$es res("!s)$e #"r&reat!% the s&atter!%(atter!*Me the"r+,

• Lar%e (art&$es- s&atter $%htat s.a$$ a!%$es /th %reater!te!st+ a!' 0&e 0ersa

• Part&$e s1e re("rte' asvolume equivalentsphere diameter.



MIE THEORY

A. Particle assumed to be spherical

• Laser '2ra&t"! s se!st0e t" the 0"$u.e "# the (art&$e

• He!&e3 (art&$e 'a.eters &a$&u$ate' #r". the .easure' 0"$u.e3)ut assu.e a s(here "# e4u0a$e!t 0"$u.e

B. Suspension is dilute

• Part&$e &"!&e!trat"! s s" $"/ that s&attere' ra'at"! s 're&t$+.easure' )+ the 'ete&t"r *5e5 s!%$e s&atter!%,

• Re6s&atter!% '"es !"t "&&ur



Laser D2ra&t"! S+ste.

3 main elements:

15 Optical bench: Laser )ea. $$u.!ates the (art&$es

! the sa.($e (rese!t "! the "(t&a$ )e!&h

• A seres "# 'ete&t"rs a&&urate$+ .easure the !te!st+"# s&attere' $%ht



. Sample dispersion unit:

• E!sures that (art&$es are 'e$0ere' t" the "(t&a$)e!&h at the &"rre&t &"!&e!trat"! a!' sta)$e state "#

's(ers"!

• Wet sa.($e 's(ers"! u!t- $4u' 's(ersa!t *a4ue"us"r s"$0e!t )ase',

• Dr+ ("/'er sa.($e 's(ers"! u!t -7"/!% %asstrea. *usua$$+ 'r+ ar,



3. !nstrument so"t#are-

• C"!tr"$s the s+ste.

• A!a$+1es s&atter!% 'ata t" &a$&u$ate a (art&$e s1e'str)ut"!

• Pr"0'es !sta!t #ee')a&8 a!' e9(ert a'0&e



WOR:IN;• The $aser )ea. e.tte' #r". the $%ht s"ur&e s &"!0erte' t" a

th&8er )ea. )+ the &"$$.at"r3 /h&h s rra'ate' "! thesa.($e (art&$e %r"u( t" )e .easure'

• D2ra&te'<s&attere' $%ht s e.tte' #r". a$$ (art&$es rra'ate')+ the $aser )ea.3 thus #"r.!% a $%ht !te!st+ 'str)ut"!(atter!

• The $%ht !te!st+ 'str)ut"! (atter! "# the #"r/ar' s&attere'$%ht s &"!'e!se' )+ the $e!s3 a!' a &"!&e!tr&a$$+6sha(e''2ra&te' .a%e s #"r.e' "! the 'ete&t!% ($a!e

• Ths '2ra&te' .a%e s 'ete&te' )+ the #"r/ar''2ra&te'<s&attere' $%ht se!s"r *W!% se!s"r, /h&h s .a'eu( "# &"!&e!tr&a$$+6($a&e' $%ht6re&e0!% e$e.e!ts

• A$s"3 s'e a!' )a&8 s&attere' $%ht a$s" s 'ete&te' )+ s'e a!'

)a&8 s&attere' $%ht se!s"rs



$ L%ht !te!st+ 'str)ut"! (atter! %e!erate' #r". % &msize particles:

• D2ra&te'<s&attere' $%ht e.tte' #r". (art&$es &"!&e!trates! the #"r/ar' 're&t"!

• C".(are' /th $%ht ! the #"r/ar' 're&t"!3 $%ht s&attere'a!' '2ra&te' ! "ther 're&t"!s s 0er+ .u&h /ea8er

• Whe! $ar%er s1e (art&$es are .easure'3 '2ra&te'<s&attere'

$%ht &"!&e!trates e0e! ."re ! the #"r/ar' 're&t"!



$ L%ht !te!st+ 'str)ut"! (atter! %e!erate' #r". 1 &m

size particles:

• As the (art&$e s1e )e&".es s.a$$er3 the (atter! "# the'2ra&te'<s&attere' $%ht s(rea's s$%ht$+ t" the (er(her+a/a+ #r". the #"r/ar' 're&t"!

$ L%ht !te!st+ 'str)ut"! (atter! %e!erate' #r". '.1 &msize particles:

• As the (art&$e s1e )e&".es s.a$$er3 $%ht t"/ar's the s'es*u(<'"/! a!' $e#t<r%ht 're&t"!s, a!' )a&8 *"(("ste the$aser )ea. tra0e$ 're&t"!, )e&".es str"!%er5 The $%ht(atter! s(rea's ! a$$ 're&t"!s =ust $8e a >&"&""!>



ADANTA;ES

• W'e '+!a.& ra!%e *su)6@ t" ..,• Ra(' .easure.e!ts * .!,

• F$e9)$t+

• H%h sa.($e thr"u%h(ut

• Ease "# 0er&at"!

• We$$6esta)$she' te&h!4ue 6 &"0ere' )+ ISOG*GG,



DISADANTA;ES

5F"r (art&$es .3 !"'st!%usha)$e

#eature ! thes&atter!% (atter!s ")ser0e'

• He!&e3 a&tua$

(art&$e s1e'eter.!at"!'&u$t



5The sa.($e &a! a%%$".erate ! the 's(ers"! .e'a %0!% $ar%er (art&$es1es tha! the a&tua$ s1e ! the (r"'u&t

5 I# a (art "# the (art&$es ha0e h%h 'e!st+3 t s ("ss)$e that se'.e!tat"!/$$ "&&ur3 a!' thus3 the /h"$e sa.($e /$$ !"t )e .easure'

K5 A &".."! err"r ! $aser '2ra&t"! s the a(($&at"! "# t"" .u&h s"!&at"!"# the 's(ers"!3 )ut #ra%$e (r.ar+ (art&$es .a+ thus %et 'estr"+e'

5 The &"!&e!trat"! "# sa.($e .ust )e su&e!t$+ h%h t" %0e a! a&&e(ta)$es%!a$ t" !"se rat" ! the 'ete&t"r

5 The &"!&e!trat"! "# the (art&$es .ust )e su&e!t$+ $"/ s" that (art&$e"0er$a( a!' .u$t($e s&atter!% s a0"'e'



REFERENCES•

Phar.a&eut&a$ D"sa%e F"r.- Ta)$ets3 Thr'E't"!3 "$u.e I )+ Larr+ L Au%s)ur%er a!'Ste(he! W H"a%

• Ma$0er!5&".

•

Sh.a'1u5&".



()A*+ ,O-

laser diffraction (1)

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