Vacuum UltraViolet (VUV) Spectroscopy of TPB films Temperature Effect on TPB Emission Lineshape

Roberto FranciniDepartment of Physics

Università di Roma Tor Vergata

Contacts:francini@roma2.infn.it+39 06 7259 4505

SLIDE 1TPB Workshop 10/19/2012

SLIDE 2

Evaporated TPB Films Layer density (µg/cm2)

Glass substrate

167

350

725

900

1175

1450

1875

VIKUITI substrate

50

74

177

317

476

769

1376

1498

Fraction of TPB in polystyrene(Weight fraction %)

1

10

20

40

Samples obtained by evaporation of TPB on different substrates

Samples obtained by dip-coating of glass substrates in polystyrene

containing TPB

TPB Workshop 10/19/2012

Investigated TPB samples were grown at the Gran Sasso National Laboratory LNGS, INFN L’Aquila, Italy

TPB Workshop 10/19/2012 SLIDE 3

Jablonsky diagram

TPB Workshop 10/19/2012 SLIDE 4

Configurational coordinatesdiagram

Absorption SpectraPhoto Excitation (PE) Spectra

PhotoLuminescence (PL) Spectra

TPB Workshop 10/19/2012 SLIDE 5

Vacuum Monochromator McPherson model 234/302Focal length 0.2 m equipped with a 30 Watts Deuterium

lamp model 632 with MgF2 window,

Spectral range 115 – 380 nm.

Closed-cycle Helium CryostatTemperature range

12 – 300 K

Measured VUV Intensity distribution of Deuterium lamp

TPB Workshop 10/19/2012 SLIDE 6

110 120 130 140 150 160 170 1800

5

10

15

Em

issi

on In

tens

ity (a

rb. u

nits

)

Wavelength (nm)

Deuterium Lamp Spectrum

128 nm

350 400 450 500 550 6000

2

4

6

8

10

Emission

Intens

ity (a

rb. u

nits)

Wavelength (nm)

1% 10% 20% 40%

300 350 400 450 5000

1

2

3

Opt

ical D

ensity

Wavelength (nm)

1%

10%

20%

40%

Emission Spectra Excited at 128 nm

TPB in polystyrene on glass

Absorption Spectra

TPB Workshop 10/19/2012 SLIDE 7

0 10 20 30 402

3

4

5

6

7

8

Integr

ated

Emission

Intens

ity (a

rb. u

nits)

TPB fraction in Polystyrene matrix (mass %)

0 10 20 30 40428

432

436

440

444

Peak

Wav

elen

gth

(nm

)

TPB fraction in Polystyrene matrix (mass %)300 400 500 600

0.0

0.5

1.0

1.5

Wavelength (nm)

Opt

ical

Den

sity

2

4

6

8

10

12

Emission Intensity (arb.units)

TPB Workshop 10/19/2012 SLIDE 8

TPB in PMMA

TPB in polystyrene

J. Huang et al., J. Lumin. 81 (4), 285 (1999)

TPB evaporated on glass

Spettri di EmissioneEccitati a 128 nm

250 500 750 1000 1250 1500 1750 2000422

423

424

425

426

427

428

Peak

Wav

elen

gth

(nm

)

TPB density (g/cm2)

250 500 750 1000 1250 1500 1750 20000.6

0.7

0.8

0.9

1.0

1.1

1.2

Emis

sion

Inte

nsity

(arb

. uni

ts)

TPB density (g/cm2)

350 400 450 500 550 600

0

4

8

12

16

20

Emis

sion

Inte

nsity

(arb

. uni

ts)

Wavelength (nm)

350 g/cm2

725 g/cm2

1175g/cm2

1875g/cm2

TPB evaporato su vetro

Emission Spectra Excited at 128 nm

TPB Workshop 10/19/2012 SLIDE 9

0 250 500 750 1000 1250 1500

0.95

1.00

1.05

1.10

1.15

1.20

1.25

1.30

Peak

Em

issi

on In

tens

ity (a

rb. u

nits

)

TPB density (g/cm2)

350 400 450 500 550 600 650

0.5

1.0

1.5

2.0

Emis

sion

Inte

nsity

(arb

. uni

ts)

Wavelength (nm)

300 K250 K

200 K

150 K

87 K

12 K

Sample A7 - 177 g/cm2 TPB-Vikuiti

0 50 100 150 200 250 3000.0

0.2

0.4

0.6

0.8

1.0

Sample A7 - 177 g/cm2 TPB-Vikuiti

Inte

grat

ed E

mis

sion

Inte

nsity

(arb

. uni

ts)

Temperature (K)

TPB evaporated on VIKUITI

TPB Workshop 10/19/2012 SLIDE 10

Emission Spectra Excited at 128 nm

mm

TPB Workshop 10/19/2012 SLIDE 11

Frank-Condon Integrals

Huang-Rhys Factor

ΔQ is the coordinate displacement between the ground state

and the excited state

T = 12 K

1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4

0.01

0.1

1

0.18 eV

TPB evaporated on VIKUITI (177 g/cm2)

Inte

nsity

(arb

. uni

ts)

Energy (eV)

(0,0)(0,4)

(0,5)

- Vibrational mode energy = 0.18 eV = 1450 cm -1

- Stretching mode vibration of trans-butadiene

S = 2

TPB in polystyrene on glass

Emission Spectra of TPBon VIKUITI and in polystyrene

Excited at 128 nmTemperatura 87 K (LAr)

TPB Workshop 10/19/2012 SLIDE 12

350 400 450 500 550 600 6500

1

2

3

4

T = 12 K

50 K

87 K

150 K

200 K

Em

issi

on In

tens

ity (a

rb. u

nits

)

Wavelength (nm)

300 K

exc = 128 nm

Emission Spectra Excited at 128 nm

350 400 450 500 550 6000

4

8

12

16

TPB on VIKUITI TPB in polystyrene on glass

Nor

mal

ized

PL

(arb

. uni

ts)

Wavelength (nm)

T = 87 K

300 320 340 360 380 400 420 440 4600

1

2

3

PE

(arb

. uni

ts)

Wavelength (nm)

(em

= 422 nm) (

emi= 445 nm)

(emi

= 460 nm)

300 350 400 450 500 550 6000

2

4

6

8

PL

(arb

. uni

ts)

Wavelength (nm)

(exc = 265 nm) (exc = 280 nm) (exc = 295 nm) (exc = 348 nm) (exc = 380 nm) (exc = 400 nm)

Campione TPB evaporato su VM2000 (600 g/cm2)

300 320 340 360 380 400 420 440 4600.0

0.5

1.0

1.5

PE

(arb

. uni

ts)

Wavelength (nm)

(emi

= 422 nm) (

emi= 445 nm)

(emi

= 460 nm)

300 350 400 450 500 550 6000

1

2

3

4

PL

(arb

. uni

ts)

Wavelength (nm)

(exc

= 295 nm) (exc= 348 nm) (exc= 380 nm) (exc= 400 nm)

TPB in polistirene su vetrino

Photoluminescence (PL) and Photoexcitation (PE) in the UV-VIS range

TPB Workshop 10/19/2012 SLIDE 13

TPB in polystyrene on glass – T = 300 K

TPB evaporated on VM2000 – 600 μg/cm2 – T = 300 K

TPB Workshop 10/19/2012 SLIDE 14

Emission Spectra (excited at 128 nm) of TPB evaporated on VIKUITI, TPB in polystyrene on glass and of a VIKUITI blank, compared with the emission spectrum of a Sodium Salicylate film on glass.

300 350 400 450 500 550 600 650

0.0

0.4

0.8

1.2

1.6

2.0

Nor

mal

ized

Em

issi

on In

tens

ity (a

rb. u

nits

)

Wavelength (nm)

Sodium Salicylate TPB/polystyrene on glass TPB on VIKUITI

Blank VIKUITI

T = 300 K