Determination of transition probabilities for the 3p fi 3s transition array in neon using laser induced breakdown spectroscopy

7 Pages·00.478 MB·English

by  Haroon Asghar, 1,a) Raheel Ali, 1 and M. Aslam Baig 2,b)

PHYSICSOFPLASMAS20,123302(2013)
Determination of transition probabilities for the 3p fi 3s transition array
in neon using laser induced breakdown spectroscopy
HaroonAsghar,1,a)RaheelAli,1andM.AslamBaig2,b)
1AtomicandMolecularPhysicsLaboratory,DepartmentofPhysics,Quaid-i-AzamUniversity,
45320Islamabad,Pakistan
2NationalCenterforPhysics,Quaid-i-AzamUniversityCampus,45320Islamabad,Pakistan
(Received5April2013;accepted3December2013;publishedonline17December2013)
We present here a study of the optical emission spectra of the laser produced neon plasma
generated by a Nd:YAG laser at 1064nm. The spectra were recorded using the laser induced
breakdown spectroscopy 2000 detection system comprising of five spectrometers covering the
entire visible region. The observed spectra yield all the optically allowed transitions between
the 2p53p upper and 2p53s lower configurations based levels. The relative line strengths of all the
dipole allowed transitions have been determined using the intensity ratios and compared with the
J-filesum rule.Theabsolutetransitionprobabilities have been calculated byusingthelifetimes of
the upper levels and the intensities of the observed spectral lines and show good agreement with
theliteraturevalues.VC 2013AIPPublishingLLC.[http://dx.doi.org/10.1063/1.4849436]
I. INTRODUCTION beenusedtoobtainthetransition probabilities ofthe neutral
andionizationstagesofdifferentatoms.4–7
Numerous efforts have been devoted theoretically and
Extensive work has been reported in the literature for
experimentally to determine the transition probabilities of
the precise measurements of the transition probabilities of
atomsbecauseoftheirimportanceinmanyfieldsofresearch
neon.ThorneandChamberlain8reportedtheabsolutetransi-
suchasastrophysicsandplasmaphysics.Inplasmaspectros-
tionprobabilitiesofNe,Ar,andKr.Nodwelletal.9reported
copy, these quantities are used for the quantitative analysis
the relative transition probabilities of 21 lines of neon
oftheplasmaplume.Inastrophysics,transition probabilities
attached to the 2p53p ! 2p53s transitions. Shoffstall and
are important for the determination of elemental abundance,
Ellis10 determined the absolute transition probabilities of 29
ionizationdegree,numberdensity,andelectrontemperature.
spectral lines by using an electron beam excitation method.
Withtheadventoftunablelasers,accuratevaluesofthetran-
Bengtson and Miller11 measured the absolute transition
sition energies and transition probabilities have been deter-
probabilities of 34 visible and near-infrared Ne lines by the
mined more efficiently. These quantities are deduced from
gas-driven shock tube method. Bridges and Weise12 deter-
theintensitiesoftheemittedspectrallines.Thepresentwork
minedthetransitionprobabilitiesof30linesofneonusinga
was started with the objective to assess the possibility of
wall-stabilized arc operating in an argon neon mixture oper-
usingLIBS(laserinducedbreakdownspectroscopy)todeter-
atingatanatmosphericpressure.Schectmanetal.13reported
mine the transition probabilities of the neon spectral lines
the absolute transition probabilities for the 2p53s ! 2p53p
due to transitions between the levels associated with the
transitions in neon using the phenomenological intermediate
2p53p and 2p53s configurations. The visible region in which
coupling wavefunctions. Inatsugu and Holmes14 measured
these transitions lie have been extensively studied using dif-
theabsolutetransitionprobabilities ofneonbythedischarge
ferent radiation sources such as discharges and sparks and
method.Subsequently,Fujimotoetal.15measuredthetransi-
monochromatorshavebeennormallyusedtoscanthewave-
tionprobabilitiesof31linesofNebyusingthemagicangle,
lengthregion.However,thereisalwaysachancethatthedis-
pulsedexcitationmethodinthepresenceofamagneticfield.
chargepropertiesmightchangewhilethewavelengthregion
Recently,Bacławski16reportedthetransitionprobabilitiesof
is being scanned. The LIBS is an interesting technique in
the 3p ! 3d transition array in neutral neon produced in a
whichalaserisusedtoproduceplasmaatthesurface ofthe
wall-stabilizedarcasanexcitationsource.
materialoringases,andtheemissionoftheplasmaplumeis
In the present work, we report the optical emission of
recordedwithininafractionofasecond,whichyieldsinfor-
the neon plasma which was recorded using the LIBS tech-
mation about the sample constituents and composition.1–3
nique, in which the entire visible part of the spectrum was
The absolute values of the transition probabilities can be
recorded within microseconds, and we believe the discharge
obtained by measuring the line intensities arising from the
properties remained intact during the experimentation. We
emission of a laser produced plasma and combining them
have observed all the 30 spectral lines of neon due to the
with the life times of the upper levels. This technique has
2p53p ! 2p53s transitions array and calculated their line
strengths. In addition, the absolute transition probabilities
a)Present address: Preston Institute of Nano-Sciences and Technology, have been obtained from the known life times of the upper
PrestonUniversity,Islamabad.
b)Author to whom correspondence should be addressed. Electronic levelsandcomparedourdatawiththeliteraturevaluesshow-
addresses:[e-mail],[e-mail],[e-mail] ingagoodagreement.
1070-664X/2013/20(12)/123302/7/$30.00 20,123302-1 VC 2013AIPPublishingLLC
123302-2 Asghar,Ali,andBaig Phys.Plasmas20,123302(2013)
II. EXPERIMENTALPROCEDURE have been presented in LS-coupling, which are optically
connected with the 2p53s configuration based four levels;
The experimental details are described in our earlier
3P and 1P , respectively. There is only one line,
papers.17–20 In brief, it consists of a Q-switched Nd:YAG 2,1,0 1
observed at 656.5nm, which does not belong to neon; it is
laser (Quantel, France), pulse duration 5ns, and repetition
the Balmer H line which appears due to the presence of
rate 10Hz that can deliver energy (cid:2)400 mJ at 1064nm. A a
hydrogen in the plasma plume. In accordance with the LS
small amount of neon gas (10Torr) was inserted in a vac-
coupling DS¼0 selection rule, only transitions between
uum chamber which was pre-evacuated to 10(cid:3)6Torr. A
singlet to singlet or triplet to triplet levels are allowed
laser pulse having energy about 120 mJ was focused
restricting the total number of transitions to eighteen.
through a 20cm focal length quartz lens to a spot of about
However, due to a departure from the LS coupling, the
0.5mm diameter. The corresponding power density was
number of allowed transitions will be 30. The appearance
1.2 (cid:4) 1010 W/cm2. The optical emission was collected
of these additional lines andtheir intensities will reveal the
through a lens of 1cm (0–45(cid:5) field of view) using a 5cm
contribution of the electrostatic and spin-orbit interactions.
diametersilicawindow,placedatarightangletothedirec-
As all the expected optically allowed transitions involving
tion of the plasma plume expansion. Our detection system
the 2p53p and 2p53s configurations based levels have been
LIBS2000 (Ocean Optics, Inc.) consists of five spectrome-
observed and the spectral lines are also well resolved;
ters, each having 5 lm slit width, equipped with 2400 and
therefore, it was tempting to extract information about the
1800 lines gratings covering the spectral region from
line strengths and experimental transition probabilities
200nmto720nmwithanopticalresolution(cid:2)0.05nm.The
from the intensities of the observed lines and to compare
data were acquired with a delay time of 3.5ls, integration
theseresultswiththeoreticalcalculations.
time of 2.1ms, and stored by the OOI LIBS software. The
spectra were recorded at different laser power densities to
rule out the possibility of self absorption in the spectral
IV. DETERMINATIONOFPLASMAPARAMETERS
lines. The data were further corrected by subtracting the
darksignalandaveragedovertenlasershotstoimprovethe The intensityof an emitted spectral line is a measure of
signaltonoiseratio. the population of the excited energy level of an element in
plasma.If theplasma isin thelocal thermodynamic equilib-
rium(LTE),thepopulationofanexcitedlevelcanberelated
III. DESCRIPTIONOFTHEOBSERVEDSPECTRUM to the total density N(T) of atoms of this element by the
Boltzmann’sLaw:22
InFig.1,wepresenttheemissionspectrumoftheneon
plumegeneratedbyfocusingthe1064nmNd:YAGlaseron hc 1 NðTÞ (cid:2) E (cid:3)
the neon gas sample. The assignment of observed spectral Iij ¼4pk UðTÞgiAijexp (cid:3)kTi : (1)
lines to the dipole transitions in the 2p53p-2p53s array was ij e
easy since the energies of the corresponding atomic levels
Here, k is the transition wavelength, N(T) is the total num-
are very accurately known.21 All atomic lines observed in ij
berdensity,U(T)isthepartitionfunction,g isthestatistical
i
this spectral region have been classified as due to transi-
weight of the upper level, A is the transition probability, E
tionsbetweenthe2p53pconfigurationbasedupperlevelsto ij i
istheenergyoftheupperlevel,kistheBoltzmannconstant,
2p53sconfigurationbasedlowerlevels.Inordertoelucidate
and T is the electron temperature. In case more lines are
e
the line assignments and their relative intensities, in Fig. 1,
observed from upper levels, then the relative intensities of
we have drawn the lines of each multiplet in different col-
the lines can be used to evaluate the plasma temperature
ors.Forsimplicity,the2p53pconfigurationbasedtenlevels
fromthefollowingrelation:
(cid:2)k I (cid:3) (cid:2)NðTÞ(cid:3) E
Ln ij ij ¼Ln (cid:3) i : (2)
gA UðTÞ kT
i ij e
A plot of the expression on the left hand side against the
upperlevelsenergiesE shouldbeastraightlinewithaslope
i
equalto((cid:3)1/kT ).Therefore,theplasmatemperaturecanbe
e
obtained without the knowledge of the total number density
N(T)andpartitionfunctionU(T).Theneonlinesusedtocal-
culate the plasma temperature are: 607.60nm, 630.65nm,
633.62nm, 638.48nm, 703.44nm, and 717.59nm, whereas
the transition probabilities A values have been taken from
ij
the NIST data base.21 These transitions are selected as they
have the largest difference between their corresponding
upperenergylevelstomaketheBoltzmannplotmoremean-
FIG.1.Emissionspectrumofthelaserproducedneonplasmageneratedby ingful. In Fig. 2, we show the Boltzmann plot based on the
focusingtheNd:YAGLASERat1064nmbeamonthegas sample.Lines
intensities of the above five lines and the corresponding
originatingfromacommonupperlevelofthe3p-3stransitionarrayofneon
areshowninthesamecolor. spectroscopic data. The line, which passes through the data
123302-3 Asghar,Ali,andBaig Phys.Plasmas20,123302(2013)
FIG.2.BoltzmannPlotforthecalculationoftheplasmatemperaturefrom
sevenlinesofneutralneon.Theplasmatemperaturehasbeendeterminedas
84006200K. FIG.3.TypicalStarkbroadened line profile of the neon line at 626.8nm.
TheredsolidlineinthefigureisafittedLorentziancurvetotheobserved
profile.TheFWHMofthelineisusedtocalculatetheelectrondensity.
points,isalinearfitofEq.(1)andfromitsslopethevalueof
the plasma temperature is obtained as 84006200K. The of the upper level increases and consequently the intensities
quoted uncertainty in the extracted plasma temperature is ofthelines alsoincrease. However,theintensity ratioofthe
mainly coming from the errors in the transition probabilities strongestlinesremainsconstantindicatingthattheplasmais
andthemeasurementsoftheintegratedintensityratiosofthe optically thin. In Fig. 4, we show a portion of the emission
spectral lines. The condition of the applicability of the spectrum of neon covering the region from 625 to 635nm
Boltzmann Plot method to calculate the plasma temperature recordedatdifferentlaserenergies,60,75,95,100,105,and
isthattheplasma shouldbe intheLTE. Onenecessarycon- 115 mJ. The three lines belong to P[3/2] ! [1/2] 3P at
0 0 0
dition that must be fulfilled for LTE is the McWhirter’s 626.82nm, D[3/2] ! [3/2] 3P at 630.65nm, and D[5/2]
2 1 1 2
criterion:22 ![3/2] 3P at633.62nmtransitions,respectively. Itisevi-
2 2
dentfromthefigurethatasthelaserenergy isincreased, the
N ðcm(cid:3)3Þ(cid:6)1:6(cid:4)1012½T ðKÞ(cid:7)1=2½DEðeVÞ(cid:7)3: (3) line intensities increase as well but their relative intensities
e e
remain constant. Thus, the contribution of self absorption, if
Here,DE(eV)istheenergygapbetweentheupperandlower any,maybeconsideredasnegligible.
levels of a transition and T (K) is the electron temperature.
e
At the highest evaluated temperature of (cid:8)9000K, this rela-
tiongivesavalueofN ffi1015.Theelectronnumberdensity V. THEORETICALLINESTRENGTHS
e
can be extracted from the Stark broadened line profiles of Warner,24 Cowan, and Andrew25 developed relations to
well isolated emitted spectral lines. The full width at half theoretically calculate the line strengths of transitions based
maximum(FWHM)ofthelineprofileiscalculatedas22
(cid:2) (cid:3)
N
Dk ¼2x e : (4)
1=2 1016
Here,xistheimpactbroadeningparameterandN isthenum-
e
ber density. In Fig. 3, we show an experimentally observed
line profile of the neon line at 626.82nm; the continuous line
that passes through the data points is the fitted Lorentzian
curve. The observed FWHM is corrected by subtracting the
contribution of the instrumental width; 0.05nm. The value of
the impactparameter for thisline isreported x¼0.078nmat
10000KbyKonjevicandWiese.23Thenumberdensityiscal-
culated as Neffi1016cm(cid:3)3 which is higher than the number
densityrequiredbytheMcWhirter’scriterionforLTEtohold.
Thus,theplasmacanbeconsideredatLTE.
In order to confirm the absence of self absorption in the FIG.4.A selected portionof the emission spectrumof neon covering the
spectra, we have recorded the emission spectra by keeping regionfrom625to635nmrecordedat60,75,95,100,105,and115mJof
laserenergies.ThethreelinesbelongtoP[3/2] ![1/2] 3P at626.82nm,
the gas pressure constant and varying the laser energy den- D[3/2] ![3/2] 3P at630.65nm,andD[5/2]0 ![3/2]0 3P0 at633.62nm
2 1 1 2 2 2
sity. As the laser energy density is increased, the population transitions,respectively.
123302-4 Asghar,Ali,andBaig Phys.Plasmas20,123302(2013)
on the Winger’s 6j and 9j symbols in the four coupling Thesummationisoverj,keepingifixed.Theexperimental
schemes;LS,LK,jK,andjj.Tocalculatelinestrengthsofdif- relativelinestrengthsarethenmultipliedbythesumofthe
ferenttransitionswithintheframeworkofWigner’srelation,it intensitiesinthemultiplet:(2Lþ1)(2Sþ1)(2L0þ1).26,27
is imperative to designate the 2p53s and 2p53p configurations Here, L and S are the orbital angular momentum and spin
based levels in these coupling schemes. In Table I, we enlist quantum number for the lower level and L0 is that of the
theenergiesoftheupperandlowerlevels,thewavelengthsof upper level. As the sum of intensities of all the transitions
the dipole transitions and the level designations in the four from a common upper level to different lower levels is
coupling schemes and in Paschen notation. The crosses in the equaltotheJ-filesumtherefore,wehaveaddedthestatisti-
table denote the optically forbidden transitions. Within the calweightsforalltheupper(2p53p)levels,andthenmulti-
framework of the LS-coupling scheme, only eighteen transi- plied it with the statistical weight of the individual lower
tionsareallowed.However,adeparturefromtheDSselection (2p53s) levels. This yields the sum of the intensities of all
rule will yield 30 transitions and indeed we have observed all the transitions from different upper levels to a common
thepredicted30spectrallines.Thepresenceoftheentirearray lower level. Similarly, the intensities from a common
oftransitionsindicatesthattherelevantneonenergylevelsare upper level to different lower levels are determined by
notadequatelydescribedbypureLScoupling. multiplying the sum of the statistical weights of the lower
Ournext task isto extract the experimental relative line levels with the statistical weight of the individual upper
strengths from the intensities of all the observed spectral level.26,27
lines.TheintensityI ofanyemissionlineisexpressedas In Table II, we present the experimentally deter-
ij
mined line intensities of all the allowed transitions in
h(cid:2)
I ¼ N g A ; (5) neon along with the sum of the line intensities and the J-
ij 4p i i ij file sum values. We have represented the levels using the
jK-coupling which clearly gives the K and j-values of
where N is the number density, g is the statistical weight,
i i the excited electron. The sums of intensities in each row
A is the transition probability, i represent the upper level,
ij are equal to the J-file sum values that validate our exper-
and j is the lower level. However, if one additional line
imentally determined line strengths. The sums of inten-
appears from the same upper level i but decays to other
sities in each column are compared with that of the J-file
lower level k then the ratio between the two line strengths
sum values showing good agreement except for those
canbeexpressedas10
associated with the 3s[1/2] lower level which differs by
0
Sij ¼ k3ijAij ¼ k3ijIij : (6) nsteraernlgyth1s4.o6f%a.llInthaeddtriatinosnit,iownse uhsaivneg cdailfcfeurleantetdcothmebilninae-
Sik k3ikAik k3ikIik tions of coupling schemes for the lower and upper levels.
It is worth to mention that a few transitions are not
Theratioofthelinestrengthsoftransitionsthatshareacom-
allowed when the LS-coupling scheme is used for both
monupperlevel isindependentonthelevel populationsand
the upper and lower levels. Similarly, a few transitions
can be directly extracted from the experimental line inten-
are forbidden in the jK or jj couplings as transitions
sities. The individual line strength can be obtained from the
between the same j-value in the lower and the upper
J-FileSumRule10usingtherelation
level are allowed whereas if the j-values of the core elec-
trons and that of the excited electron are different then
2 3(cid:3)1
Sik ¼ðð22‘jiiþþ11ÞÞ41þXj6¼k kk3i3ikjIIiijk5 : (7) tnhaetiotrnasnsinitiwonhsicahreallfotrhbeidtdraenns.itTiohnesrearaerealolonwlyedtw; eoitchoemr LbiS-
coupling for the upper level and LK for the lower level
TABLEI.Levelenergies,transitionwavelengths,andleveldesignationsinthefourcouplingschemes.
Upperlevelenergies(cm(cid:3)1) k(nm) k(nm) k(nm) k(nm) LS LK jK jj
2p 152970.73 585.41 (cid:4) 540.21 (cid:4) 1S S[1/2] 1/2[1/2] (1/2,1/2)
1 0 0 0 0
2p 151038.45 660.08 616.53 603.17 588.35 3P P[1/2] 1/2[1/2] (1/2,3/2)
2 1 1 1 1
2p 150917.43 665.39 (cid:4) 607.60 (cid:4) 3P P[1/2] 3/2[1/2] (3/2,3/2)
3 0 0 0 0
2p 150858.51 668.01 (cid:4) 609.79 594.65 3P P[3/2] 1/2[3/2] (1/2,3/2)
4 2 2 2 2
2p 150772.11 671.89 626.82 613.02 597.72 1P P[3/2] 1/2[3/2]1 (1/2,1/2)
5 1 1 1
2p 150315.86 693.14 (cid:4) 630.65 614.48 1D D[3/2] 3/2[3/2]2 (3/2,3/2)
6 2 2 2
2p 150121.59 702.60 653.47 638.48 621.90 3D D[3/2] 3/2[3/2] (3/2,3/2)
7 1 1 1 1
2p 149824.22 717.59 (cid:4) 650.83 633.62 3D D[5/2] 3/2[5/2] (3/2,1/2)
8 2 2 2 2
2p 149657.04 (cid:4) (cid:4) (cid:4) 640.40 3D D[5/2] 3/2[5/2] (3/2,1/2)
9 3 3 3 3
2p 148257.79 808.47 744.10 724.72 703.44 3S S[1/2] 3/2[1/2] (3/2,1/2)
10 1 1 1 1
Lowerlevelenergies(cm(cid:3)1) 135888.71 134818.64 134459.29 134041.84
1s 1P 1s 3P 1s 3P 1s 3P
2 1 3 0 4 1 5 2
123302-5 Asghar,Ali,andBaig Phys.Plasmas20,123302(2013)
TABLEII.ExperimentallinestrengthsandJ-sumRule.
Levels 1s 3s0[1/2] 1s 3s0[1/2] 1s 3s[3/2] 1s 3s[3/2] Total J-sum
2 1 3 0 4 1 5 2
2p3p0[1/2] 11.86 0.14 12 12
1 0 (cid:4) (cid:4)
2p3p0[1/2] 17.4 7.48 3.46 7.66 36 36
2 1
2p 3p[1/2] 0.07 11.93 12 12
3 0 (cid:4) (cid:4)
2p 3p0[3/2] 29.8 16.73 13.47 60 60
4 2 (cid:4)
2p3p0[3/2] 19.95 12.86 0.44 2.75 36 36
5 1
2p 3p[3/2] 27.16 6.09 26.75 60 60
6 2 (cid:4)
2p 3p[3/2] 1.72 10.03 22.15 2.1 36 36
7 1
2p 3p[5/2] 4.29 35.63 20.08 60 60
8 2 (cid:4)
2p 3p[5/2] 84 84 84
9 3 (cid:4) (cid:4) (cid:4)
2p 3p[1/2] 0.19 0.38 11.99 23.44 36 36
10 1
Totallinestrength 112.4 30.75 108.6 180.3 432 432
J-sum 108 36 108 180 432 432
Difference% 4.10% 14.60% (cid:3)0.5% (cid:3)0.28%
or LK coupling for the both upper and lower levels. In here, Pn Iij are the branching ratios of the intensities from
our experimental results, the transitions from the 2p53p theuppejr¼l1eIvikelitojandklowerlevels,whereastheradiative
1S level to the 2p53s 1P and 3P levels and from the lifetimes oftheupperlevelisdefinedas
0 1 1 i
2p53p 3S to 2p53s 1P and 3P levels have been
1 1 2,1,0
observed furthermore the intensities of the lines follow- n !(cid:3)1
X
ing the DS¼0 selection rule are dominating. The s ¼ A : (9)
i ik
observed line intensities of the 2p53p 1S ! 2p53s 1P , k¼1
0 1
3P transitions are in the ratio 1000:25 that is an indica-
1
tion of a departure from LS coupling. Thus, the coupling Equations (8) and (9) can be used to determine the absolute
scheme in which the singlet to triplet transitions will A values from the known life time of the upper levels.
ik
gain some intensity is the LK coupling of Cowan and Fujimto et al.30 reported the life times of all the ten levels
Andrew.25 A similar situation is observed for the transi- based on the 2p53p configuration. Incorporating the experi-
tions from the 2p53p 1P1 level to the 2p53s 1P1 and mentally measured line strengths from these upper levels to
3P2,1,0 levels and from the 2p53p 3P1 to the 2p53s 1P1 different lower levels, we have obtained the absolute values
and 3P2,1,0 levels. When we compare the experimental of the transition probabilities for all the 30 transitions. The
line strengths with the theoretical line strengths, we mainsourcesoferrorsintheobtainedtransitionprobabilities
noticed that there is not a single coupling scheme which are the uncertainties in the life times of the upper levels
completely agrees with all the observed line intensities. (2%–4%) and in the measurement of the integrated line
However, the LK coupling scheme for the lower as well intensities of the spectral lines (5%–10%). Thus, the overall
as for the upper levels seems to be a useful scheme for uncertainty in the absolute values of the transition probabil-
the level designation for the 2p53p to 2p53s configura- itiesdoesnotexceed12%.
tions based levels in neon. We believe there is a need to In Table III, we report the transitions in jK-coupling,
modify the formulas presented by Warner,24 Cowan and vacuum wavelengths (nm), the absolute values of the transi-
Andrew,25 and Cowan26 to accommodate the transitions tion probabilities determined in the present work, the abso-
from different j-values of the core electrons and that of lute values listed in the NIST21 data base that are the same
the excited electron. values reported by Inatsugu and Holmes,14 the life times of
the excited levels as listed by Fujimto et al.30 and the last
VI. ABSOLUTETRANSITIONPROBABILITIES columncontainsthepercentagedifferencebetweentheNIST
In order to measure the absolute emission transition data and the present work. Our experimentally determined
probabilitiesA fromanupperlevelitolowerlevelsk,itis absolute values of the transition probabilities are in good
ik
important that the life time of the upper level is precisely agreement with that of the earlier work and that of the NBS
known and second the relative emission intensities I /I values except for a couple of lines. Thepercentage differen-
ij ik
from the upper level i to all the lower levels are known. A ces between the reported values and the present measured
generalrelationtorepresenttheabsolutetransitionprobabil- values remain less than 20% except for the 621.90nm line
ities of the lines from a common upper level i to j and k which is about 48% and that of the line at 597.72nm that is
lowerlevelsisgivenas28–30 39.6%. These differences may be attributed to the errors in
the measurements of the line intensities from the observed
Aik ¼(siXn Iij)(cid:3)1; (8) spproecbtarbuimlit.ieHsobweetwveere,nththeeopvreersaellntcloymmpeaarsisuorendovfatlhueestraanndsittihoant
I
j¼1 ik oflistedintheliteratureisquitegood.
123302-6 Asghar,Ali,andBaig Phys.Plasmas20,123302(2013)
TABLEIII.ComparisonoftransitionprobabilitieswithNISTdatabase.
k(Vac.) Presentwork NIST Lifetime Difference
Transitions nm A*106 A*106 s(ns) %
3p0[1/2] !3s0[1/2] 585.41 67.967.5 68.2 14.560.2 0.4
0 1
3p0[1/2] !3s[3/2] 540.21 0.960.1 0.9 0
0 1
3p0[1/2] !s0[1/2] 660.08 22.462.5 23.2 18.560.2 3.4
1 1
3p0[1/2] !3s0[1/2] 616.53 11.661.3 14.6 20.5
1 0
3p0[1/2] !3s[3/2] 603.17 5.8760.6 5.61 (cid:3)4.6
1 1
3p0[1/2] !3s[3/2] 588.35 13.961.5 11.5 (cid:3)20.8
1 2
3p[1/2] !3s0[1/2] 665.39 0.2760.03 0.29 17.560.2 6.9
0 1
3p[1/2] !3s[3/2] 607.60 56.866.2 60.3 5.8
0 1
3p0[3/2] !3s0[1/2] 668.01 21.762.4 23.3 19.460.2 6.8
2 1
3p0[3/2] !3s[3/2] 609.79 16.0161.76 18.1 11.5
2 1
3p0[3/2] !3s[3/2] 594.65 13.861.5 11.3 (cid:3)22.1
2 2
3p0[3/2] !3s0[1/2] 671.89 24.962.7 21.7 19.860.2 (cid:3)14.7
1 1
3p0[3/2] !3s0[1/2] 626.82 19.562.1 24.9 21.6
1 0
3p0[3/2] !3s[3/2] 613.02 0.7260.08 0.67 (cid:3)7.4
1 1
3p0[3/2] !3s[3/2] 597.72 4.9060.54 3.51 (cid:3)39.6
1 2
3p[3/2] !3s0[1/2] 693.14 18.862.1 17.4 19.660.2 (cid:3)8.01
2 1
3p[3/2] !3s[3/2] 630.65 5.660.6 4.16 (cid:3)25.7
2 1
3p[3/2] !3s[3/2] 614.48 26.662.9 28.2 5.6
2 2
3p[3/2] !3s(cid:2)[1/2] 702.60 1.8960.21 1.89 19.660.3 0
1 1
3p[3/2] !3s0[1/2] 653.47 13.6461.5 10.8 26.3
1 0
3p[3/2] !3s[3/2] 638.48 32.163.5 32.1 0
1 1
3p[3/2] !3s[3/2] 621.90 3.3160.36 6.37 48.1
1 2
3p[5/2] !3s0[1/2] 717.59 2.660.3 2.87 20.660.3 9.4
2 1
3p[5/2] !3s[3/2] 650.83 28.563.1 30 5
2 1
3p[5/2] !3s[3/2] 633.62 17.461.9 16.1 (cid:3)8.1
2 2
3p[5/2] !3s[3/2] 640.40 52.0865.73 51.4 19.260.3 (cid:3)1.3
3 2
3p[1/2] !3s0[1/2] 808.47 0.1260.01 0.12 25.960.4 0
1 1
3p[1/2] !3s0[1/2] 744.10 2.7260.30 2.31 (cid:3)13.8
1 0
3p[1/2] !3s[3/2] 724.72 11.4261.26 9.35 (cid:3)20.4
1 1
3p[1/2] !3s[3/2] 703.44 24.3662.68 25.3 3.7
1 2
VII. CONCLUSIONS Physics(NCP),HigherEducationcommission(HEC),Pakistan
Science Foundation Project (PSF-134), and the Quaid-i-Azam
The branching ratios of intensities for 30 spectral lines of
University(QAU)Islamabad,Pakistan.
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