2Phat tri~n Iy thuy~t Shottky vai tr"ong hgp tdng quat: H6n hgp n chol khi co chu Y cac 10Qi vo chQm ion hoa khat nIl" ion hoa tlrng b{lc, ion hoa Penning, chuy~n di~n tich v.v.... NhQn
Trang 1TRAN .TUAN
CUA MOT LO~I LASER HON HQ"P 2 KHI
QUANG HOC - 10218 16M TATLUk.NAN PH6 TlEN sT KHOA HOC
ID~~~i; -III
\"'d"_"'-"'" " " ,, ~ \
,q, " ~ r-~-~' '~' 1
-~
THANH PHO Hb CHI MINH - 1986
Trang 2-\
CONG TRINH &UOC HOAN THANH -'iAL~~~'~_d TRUONG e~1 HOC TONG HQP TP.- Hb C.HrL- MINH-¥ '
NgU'ai hU'ang don khoa hQc:
NGUYEN HO'U CHI, Pho Tien s7, Giao suo I
NgU'ai nh{m xet 1 :
&INH VAN HOANG, Tien s7, Giao suo I
NgU'ai nh9n xet 2:
T~ vAN TUAN, Pho Tien sT.
Co quan nh9n xet:
Phon vi~n Khoa hQc Vi~t Nam
lu9n an se dU'gc boo v~ iQi H9i d6ng thOrn lu9n an Nha ""~at
hQp tQi
Co th~ tim hi~u lu9n an tQi ThU'vj~n TrU'ang &Qi HQc T6n9 H9P Thanh ph6 Ho Chi Minh
Trang 3V9' Iy laser 'rang may chvc: nC'lmg~n day pha' tri~n r6t nhieu, nhU'ng"!u trung co th~ chia lam 2 lannvlfe:'
(i) Tim cae dge frU'ng d9ng hQe va d9C trU'ng khuech dQi e~a mol trU'o-nghoQt tinh
(ii) Xae dinh d<;1ctrU'ng cuo quafrinh phat va nhi}ng dQC
trU'ng CUObCre XQ ph at d6i voi mo; trU'crng hoQt tlnh eho tnrac VEin de thCr2, ph", thuge nhieu ve Iy thuyet h~ e9ng hU'ang,
con van de thCr nhEit- moi trU'crng hoQt tfnh
a6i vai laser khf, moi trU'o-ng hoQt tlnh thlfc chEif la trQng thai plasma Trong nhfrng ni]m gan day, vi~c nghien eCrucac
thong 56 co ban cuo plasma Irong laser d~ dieu khi~n eong suEit phaf da Ira nen quon trQng Tuy nhien vi chU'a xac djnh dugc qui lu{tt dong dQng, nen phon Ian cae eong trinh deu .
du-ng IQi a duo-ng cong thlrc nghi~m voi cac thong 56 v9t Iy
cho trU'crc, cua tu-ng vQch ph61 laser
Qui lu{1tdong dQng trong IrU'crng hgp t5ng quat rEit phCrc tQP va cO tn§ khong ton 1<;11,vi v{ly cong trinh nay tren co sa
phon tfch cae qua trlnh can bang dl}ng hQc va nhi}ng qua trlnh
thuyet nhfrng thong s6 dong dQng eua loser khf, a dieu ki~n t6i U'u, trong do co ch~ kfch thfeh mCrc laser tren b&ng va ch<;tmkhong dim hoi 10Qi2 dong val fro chu yeu
Ket qua nh{1n dU'gc cuo cong trion nay khong nhi}ng gap
phon giai thfen co chg hoQt d909 cuo 10Qi laser tren, ma con
co th~ dung cae bi~u thll'C cua chung d~ xac dinh cac thong s6
v9t Iy trong che tQo cung nhU' Slr dvng.
B.- N9\ DUNG lU~N AN lu{tn an gom 3 pheln chu yeu.
I - Phan t6ng quem t6ng kef co phon Hch nhi}ng c6ng frinn
nghien cCruve mol trU'crng h09t Ifnh cuo laser khi, d~ lam co
Sa eho vi~c kneosat cae qua trinn co ban, eung nhU' Cae qua
trinh d9ng hQe trong c{>tdU'O'ng plasma loser vai eac n9i dung sou:
Trang 4- Tom hr<?,e cae qua trinh kich thich ehu yeu trong moj
trU'ong ho<;lttlnh cuo laser khf I qua trinh kich thich do va chQm di~n flr i va ehQm khong dan hoi 10Qi2 e9ng hU'ong, qua frinh
chuy~n di~n tich va ion 1'100penning
- Phon tich Iy Ihuyet va Ihllc nghi~m v~ tiet di~n va chQm khong dan hoi cuo cac qua lrinh kkh thich noi tq?m d6i vb' Iaser hen hgp 2 khi
- Khao sat ham phon b6 theo v{m toe cuo di~n tli va m9t so h~ qua quon trc;>ngcuo phU'ong trinh Boltzmann sur '9ng: phU'ong trInh can b&ng hQI, djnh lu{11 dong dQng va
dong i il{ khutkh tan va d9 linh 09ng cuo hQt trong di~u ki~n
khf Lorentz
- Phon Ifch cac qua trinh 09ng hQc cuo laser He-Ne va
laser ion hoi kim 10Qi o~ xac djnh co che kich thich chu y'u
cuo cac mlrc laser tren va dU'ai
I 1.- Phan Ihl{c hanh :
Boy la phan trQng tam cuo ban lu{1nvan B&ngphon tich
Iy thuyet tong Irlnh da 11mdU'gc qui lu{1t d6ng dc;mg d{lc trU'ng cho loQi laser khf noj tren 0 che d9 phal toi U'u N9i dung nghien ClrU boo gom:
I Phon loQi laser Iheo co the
- laser vai va chQm knong dan
kfch thich mlrc laser tren:-hOi 10Qi2 c9r.g hU'ong (L~)
Ao + 8m -+ At + Bo + 6E ; (I)
0 do A,B nguyen tli khf co ban va- khl-d~m i ky hi~u o,m,t
trQng thai co ban, siau ben, kfch thleh (mlrc laser tren), 6E
-bien dbi n9i nang cuo h~ VI dV laser He.Ne co 3 "Qch ph6t lU'ong lrng vai cac chuy~n mlrc 352- 3P4 ( ~390nm), 2s2 - 2p4 l1150nm)va 352 - 2p4 (632,8nm).
- Laser vbi va chQmion hoo Penning (loP).
+
Trang 5. +
a d6, At - m(rc ion kith thfch, vi dv trong laser ion hO'ikim loQi nhD'ng m(rc 3d'1 4s~ cuo InlI, 4d9 5s:l cua CdII / 6p cua SolI
- Laser vai qua trlnll chuy~n di~n Hcll (L.C)
+
a do, Bi ion khf d~m a trQng thai cooban, trong tr"ong hgp
nay At ntlm g(}n m(rc Bi / vi dv trong laser ion hO'ikim 10Qi nhCi'ngm(rc thu9c nhom 3dl0 nx cua lnll ,4dl0 nx cua CdII, 5s:l5p3 (200) cuo 10dIl
2Phat tri~n Iy thuy~t Shottky vai tr"ong hgp tdng quat: H6n hgp n chol khi co chu Y cac 10Qi vo chQm ion hoa khat nIl" ion hoa tlrng b{lc, ion hoa Penning, chuy~n di~n tich v.v !lr dieu ki~n m{lt d9 nguyen tv sieu bell nm khong phI,' thu9c VQOban kinh r:
.,J,
~m~
a do IJm - xac xuot pha vcr nm do va chQmdi~n tv, Om - h~
trinh can btlng hQt mang di?n trong c9' d"O'ng plasma nIl" sau:
"
£k on
~k
(2/405)2
" - R2
kT e
L
k=1
a do; Zk ~k - v9n toe ion hoa va d9 linh d?ng cua ion khf
k, a dieu ki~n plasma kh6ng co qua trlnh 2 bQCthl kef qua se
trung '/aj Iy thuyat Sh~l!ky vai n = I, va trung vai Iy thuyet Dorgela vai n==2.
3 NhQn d"9c dieu kj~n dang dQng cua plasma phong di~n khi, khi co qua trlnh 2 b{1c.
Trang 6M9t thong so v{lt Iy bot ky !rong laser khi deu phv thuge nhieu thong so khae PhU'ong phap dong dc;mg eho to sop x~p cae so li~u 6y m9t each hgp Iy nhat, don gian nh6r .Trong plasma ph6ng di~n Ihong thU'ong do c6 qui lu{lt dong dQng, ve
dong, vai gia thi~t co ban la trU'ong th~ IQi 2 di~m tlTong Ilng
trong ph6ng di~n 10 b6t bien Qui Iu{lt d6 khong ap dvng dlTgc tho laser khf, vi 6 day phai c6 dinh nghTa khat trU'ac tong su6t phat la bat bien
Tli qui lu{lt nay do rut ra dU'gc :
a d6 CJ( -nOng lU'gng trung binh bj m6t do t6t co va
cua dl~n Ilr, c-nOng lU'gng trung binh cua di~n tlr, Ne
d9 di~n Ilr, p - ap su6t
Tli h~ thlic (6) tho to kh&ng dinh rang, ngay co ktli di~n
trlTong rut- gQn E/p giong nhau trong 2 ph6ng di~n, thi' v9n roC di~n Ilr chi bang nhau khi khong c6 qua trinh 2 b{lc:,' hay c6' qua Irinh 2 b{lc , nhU'ng Ne /p la dQi IlTgng b6t bf~n
4 Xu6t phat tli phU'ong Irinh d9ng hQc tong trinh do tim dlTgc dieu ki~n toi U'u va cac thong so dong dQng cua loQi laser khi n6i tren
01 M{li d9 dao 19n lei U-u(D,Nlopt
Mal do dao Ion eua laser dU'oe xae dinh b6i:
ehQm
- mQt
gt
a d6, gt ' dd ' Nt ' Nd - trQng Iu-gng th6ng ke va mQt d9 don
so tlTong Ilng vai mile laser tren (t) va mile laser du-ai (d),
Nt ,Nd dU'ge xae dinh tlic{lp phU'ong trinh v{ln toe, va bang:'
/ eB
.
Nt = Ne NoA NoB \Qom ve \ Qt vr tZmB-/ Wgt (8)
Trang 7,Nd=N2eNoA(Q~t va) (Qilve)CGjA/Wgd
vai NoA ' NoS ~rTI{1td9 khf eo bon (A) va khf d~m (8) a tr~mg
, Wet ' Wgd ~ ,!x6'c,' su~t siam kfch thfCheae' mc,e laser;
~iX - thai sian s6ng cua nguyen tu- X a mere i;
/
. Q~X v )- hbng so v{1ntoc kfch thfch nguyen tu- X tlr merc
i I~n mercido va chQm di~n tu-,
(p~A YT )-hbng so V{1:1toe kfch thfch merc ~a$er tre~ _,(f)do
, (9)
va chQm khang dan hoi loQi 2,
Tu- di~u ki~n ClfC trj va m{1t d9 di~n tu-:
l) (,6,N) = 0
,'"
-fa 'nh{in dirgc:
(" )
k ,., ,; )' "
0, do, t<-tt _so ap suet rieng phbn; Dl'A -h~ so khuy~ch ton cila'" I .
kM-A a ti'Qng thai nO'ngIlTgngi,' a diau' kj~n chubn r = 273 K,
P = I torr.N~u ham phon bo theo nOne IlTgng cua di~n IIi la M tixwellthi cae; h&ngsov{1ntoc kfch Jhfch va ion hoa ng~JY'~n
ili la nhO'ng ham.o cud nhiet do dien t~ T ,do do (N ip ) t
Trang 8
ehi thuge voo m9t dQi h'Q'ng duy nh6t 10 Te'
Thay (II) voo (7) to nh{m dl1Q'em9t d9 dao 19n toi I1U:
12,405)2W gd ' K2 ( AN R2
a d6,
/ BA \ / e8
)
2
\Qt .VT / \ Qm ve
k
Trong eae bi~uthlrC (II), (13), (14) d6i vai vQch phat laser(L.R)
i 10 mlrC sieu ben 1m); d6i vai eae vQeh ph at laser (L.P) (' CI
i 10 mlre eo ban ion (i).
b) Nhi~t d9 di~n tir t6i I1U.
Tu- bi~u there (13), c6 th~ rut ra dl1ge 2 h~ qua quan trQng
- 1/ Val K eho trU'ae m9t d9 dao 19n toi I1U (LlN R2)Opt
Itlnh theo don vi lCR2)chi ph., thu9C voo me}tthong so duy nh6t
10 10,neu ham phon bo theo v9n toe cua di~n tir 10 Maxwell thi
thong so d6 10 Te .
- 2/ Nhi~t de} di~n tir (Ta )opt dU'Q'cxac dinh tu-dieu ki~n;
)
(-.t~- (~iA v.) (Q~Av.) \ - 0
(I-')
Trang 9Trang bi~t.lth(re (15! cae h&l1g$0 v{m t6e chi phv thu9c veo cae hang so dC}c tnrng eho loQi kIll nhU' Vi ' Vm' Vd' VI v{1y n9hi~m tOng quat cua phU'ong trinh (15) c6 dc;mg
Tli (15) 'to nh{1n dU'ge bj~u there CliO nhi~1 d9 di~n tll t6i U'u ITe )opt trong 3 trU'cmghgp
' Vai laser (loR)
(T~)~pt ' +[2(V 2 IS -Vlsk ) - (V2P + Visk ) +
~[2(V2 IS - Visk )- (V2p4 1 V'Sk)J2+ 16(2V21S-V2p4)
(1/2
J
- Vai laser (loP)
ITe )opt = -i~ [2 (V2' So-ViM) -v d + ~[2(V23S,-ViM)- Vd]2
~1/2
]
+ 10 (2V235 - Vd)ViM~ (18)
- - Va; laser (L.C)
a cf6r =- + I -3.~~A: B2 11f2I
(190)
<P= arc cas (q/r3) (19b)
(1ge)
Trang 10v6i AI 8, C, D la eae ham so cua cae hong so nguyentli,
Vi' Vm, Vdl Vi tlr (17.19) suy ra r6n; (T.) opt = conlt 9ay \a dQi Iu-gng bat bien co bon nhat vi tlr do co th~ XQ-C dinh cae dQi Iu-gngbat bien khat Tlr (161va (121cho ta :
(Ne / P)opt = const, (201
9ay la dQi Iu-gng bat bien thCr2 nh{1Odu-gc trong lo r khf a
the dt} phat tal u-u 9Qi Iu-gng bat bien nay kh&ng dinh rbng, m9c du trong laler khl co ton fQi qua trinh 2 b{lc, qui lu{lt dong
-cJ TI so ap suet ri€mgphon Kopt.
9ieu ki~n t6i u-u cua h~ so Kopt du-gc vH~tra tlr dOng thCre:
ado NA + , NB + la ndng dt} ion khf COban (AI va khf d~m-(B) trong ct}t Gu-ong plalma cualase,r ClIng vai phu-ong t,in-h can b6ng hQt ta nh{ln du-gc bi~u there cua Ii 0 ap uat rleng phon toi u-u Kopt:
- V6i laser (LR):
K w J-~
[ZO~ !-L°B~ - ~,oBB + ~
(loA !-LG~!\_ opt 2 ZOB fLoAA ~ °<~A - t ZOB !-L°AA
fLOB~
)2 + 4 loA !-L°BB/12
]
(22)
Trang 11- Val loler (loP) :
/L AB - k ZomB
B /LoBB
(23)
~
- Vai laser ll.C) :
0 /L0B~ ) I
~, AB
(24)
Trong cae bi~u there (22 24) ky hi~u zo la v{m toe cuo qua trinn ion h60 a dieu ki'~n chuan IT = 273K, p = I Torr),
NhlT v{ly, ti 10 ap luat rieng phdn cuo laser khi' 2 chat chi phI,! thu9c VaG I dQi IlTgng duy nhat 10 (Te) opt N61 each knae, (K)opt 10 I dQi IlTgng bat bien:
dl Th8ng so dong dQng tal lTU(PR)opt
Tu- phlTang trinh con baug di~n lich trang cQt dlTanl plalma cua h5n hgp khi (5), ap dvng dieu ki~n foi lTU (21), to nh{ln dlTge thong so dong dQng toi lTU(PR)opt :
. - Vai laser (loR):
(PR)opt = 2,405 (T.) opt (K + I)
Trang 12[2Z~ (K:I /L~A + K/L~B) ]
,1/2
/LBA IJ-BB
(26)
- V6i laser (LP):
(PR)opt = 2,405 Tn [ (T.) opt IJ-~B
]
1/2
(27)
- V6i laser (L.C):
T
!
° (PR)opt = 2,405 ~ -~~~~_~et
.!
1/2
273 2(Zo .1
0-B - K Zc
(28)
NhU' v9Y, (PR)opt cDng 10 m9t dQI lU'gng bot bien:
(PR)opt = f IT ) opl ' (29)
el Dong phong di~n loj U'U:
Dong phong di~n trong c9t dU'ong plasma v6i ban kfnh
R eo dQng:
J = 2J(e~'e EJ~ rNe (r) dr ; (30)
linh d9ng cuo di~n tll', E - di~n trU'ang tren trve c9t dU'ong TII (30 eta rut ra dU'go:
(J/R)ept = CX~2A-~o (A-eo v ) G (Te) !PR)~pt ; (31)
Trang 13v6'i C = 1,36 (~r/4
1~~~" .\~~~~"~ ;' ,' ~.'.'L'.\
-1 L-:r "';;1 "._1
gd gt Wgd W ( D ) ;
gt IA
II
( BA .
)( eB )
(L Q:AvT) (Q~A ve) ( Q~A Ve);
A.eo - khoong duang h! do trung binh cuo di~n hi trong c9t dU'ong v6'i ap suet p = I torr, Tn ::c 273K
NhU' v9Y, IJjR)opt chi phV thu9C VaG (Te ) opt Noi cach khat IJjR)opt la I dQi lU'gng bat bien
§ 5 So sanh Iy thuyet nh9n dugc voi thllc nhi~m
SiT dvng cac bi~u thllc da Jim ra trong § 4 d~ tinh nhi~1 d9 di~n hi toj uu (Te ) opt' ti so ap suet rieng ph?!n toi U'U Kopt ' thong so dong dQng (PR)opt , va dang phong di~n to; U'u Jopt' trong tlrng trU'ang hgp cv th~ cuo m9t so vQch phat IOU day:
(i) voi loa.r (l.R) vQch ,hat dugc khoo aat la 632,8nm (352- 2p4) cua loa.r H - N
(ii) v6'i laser (L P) cae vQch phat dugc khao sat la 441,6nm 15a22Ds/2-5p1 Ps/2)' 325,Onm (5S22DS/2-5p2 Pll2) cuo laser He - Cd, 747,8nm 14.2:1Dsl2-4p2 Ps/2)' 589,4nrri (4522
Dsl2-4p2 P1i2) cua laser H - In, 684,4nm (6p2 P1/2- 6.2 51/2) va
645,3nm (6p2 Psl2-6v 51/2) cua las.r He-So
(iii) voi laser (l.C) cae vQch poot dU'gc khao sat la
758,8nm (5p2 P'Ih - 55:1Sl/:JJ cua lo r H - In, 522,7nm (5p4
Trang 14'.0°,',:".014P5f':!)cua4ase'r?He-S~, 507,8nm (103.106°, :: a559~5/:1) , 7,~~,n' ,t 'J" - b~,j8} '0 ' <,72
cua laser tte-J~~/9~:~!5,IJm(99~85312-835771/2) cua laser Ne-Te
va 504,7n~ (61p3 D2t- 61 S3DO), 576,Onm (61 p3 D2-61 S3 Do) ,
Ci"I;};""":"":',~/"'-~" 2 7 612t7,nrn.{61p3)Pi~-,61,s8P., " 2)cua laser He,,"!" ' , Ket que c!lffh~' dU'gctrlnh bay trong' bqn lu{1n vOn
.,":,'
,NH~N XET KET QU';;:
1/ Sosanh ket qua tinh loan Iy Ihuyet(th~o cac bi~u thCrc 17'~19j, :22.,:":,24/26,~ 28;'31) va cac gia trj Ihl{C nghi~m hheo' c&-ccQng"I'rinhdadlTOC cong bolren nhi~u tgp chi khac nhau) cutf'26c 'th'&'ng's6>cto.ngdQng de) opt' !Klopt ' (PR)opt
va (Jlopt tlTong Crr)gvai cac vQch phat laser (loR) (i), laser (loP) Iii) va laser (loCI (iii), to thay rang, co 51{phu hgp kha tot giiia
Iy thuyet va Ih'lc nghi~m TCrcac ket qua nay hoan loan tho
10 kh&ng ~inh rang, 5 thong so dongdQng Iren la dung
2/Trohg5 thongso;d9r'19 dQng tren, thong so (Te) opt la
q\j'an trQ'rignhal.TCr cae bi~u thCr, (19-21) sur ra r&ng, (Te) opt chi ph"" thu?c vao nOng IlTgng cac mCre cuo khf tro va hoi kim JoQi day la nhii'1g dQi IlTgng da dU'ge khao sat chfnh xae, do
'~o ITe) opt 16 dang"ti:h C9Y Hon niJa, bi~u IhCrc(Te) opt nh9n
'dlTgc Ill' el{CIri cue, (!,5L trong do chung khong ph\) Ihu9C VCfO
gia frj tuy~t do; CUOcac' h&ng so v9n foe, ma chi phI} thu9C vao dQng,dlTong.cong"d'6ng tin c9y'cua '-chung
~oi v6i >c:a'~vQ'th;'P't1C5floser (loC):"dongphong di~n Jop:" rat Ian hon lopf ciia~'cac vQch phat'laser IloR( va (loP), nen ,.qUo trlnh l.;ng,.,b{1c 9"i'Pt5y d6ng val fro,Iqvan trQng Do d6 (Te) opt cuo laser (LC) ,nhe') hon Ic1ser (l~RIva laser (loP) \6 h,gply , ,:::':"'rn 'L ' ~"
j ", 3/ Nho co di,~u kj~-{btoj U'u( K)opt i' neri';cac bi~u thCrc do;
Y;6;i\P~)opr p'(L9iqJ)"h:r:~~ dU'ge m9,t so- h&hg ,so nguyen I";, cub
Trang 15hO'i kim loQi (den nay con chtla dtlgc nghien Cll'U day au), chinh dieu nay tho phep chung fa de dang tinh dtlgc thong so (PR)opt d6i v6i baf ky laser HeI - M va N. - M
"
I
4/ Thong s6 dong dQng (J/R) hay tNe/p) cua laser ion hO'i kim loQi da dtlgc s,p sanh gili'a Iy rhuye! va thY'c nghi~m CUI;) nhieu tat g1o ~h6'c nha.u d6i v6i vQch phat He , Cd (l.P) va laser H~-I (loCI SY'phu hgp co ve quy lu{u bien obi, co ve gia Irj tuy~t d6i cua !hong s6 dong dQng (J/R) chll'ng 10 rang, Ne/p nh~andtl<1c Ill' Iy huyella hoan loanphu -hgp
51 6 che, d9 phal 'tlO'l1g(rng v6i dong phaog di~n nho,Jhl dieu ki~n (4) sa bj vi phQI11 16n &ieu d6 tho ta doan" nh{jn
rang, a day se khong ton tQi cac thong 56 dong dQng.
III KET LU';N
I I Xuat phat fll' phU'O'ng frinh d9ng hQc cua laser adieu ki~n tong suaf phot toi U'U,va fll'gill thiet (.~N, R2jopf = cons!' mch da eMnden cac thong s6 dong dQrig (TeJ opt ,"(PRIopt,
Hai thong s6 dong dQng (N e/P) opt va (J/R) "opt khat v6i cac thong 56 dong dQng tU'O'ng(rng trong c9t dtlO'ng thong fhU'ang la Ne Ip2 va J (nh{jn dU'gc tll' gio thiet V ==const) 2/ S,! phil hgp gili'a Iy thuyet va thY'c nghi~m v6i nhiiu tat gill khat nhau d6i v6i vQch phat khat nhau ch(rng to rang:
a) Quy lu{jf dOng dQng a fren la dung.
b) NhiJ'ng qua frinh djch chuy~n chu yeu d~ tQo moi trU'ong
cl M9C du cac qua frinh kith thich mang tinh chat fling b{jc, nhtlng fhoa man dieu ki~n INe/P) = const, nen thoa man dieu ki,n dong dQng (hinh hQc) trong plasma ph6ng di~n khi'