Letters to the Editor: Eighteen new laser dyes generating in the visible spectral range

Optica Applicata, Vol. XIV, No. 2, 1984

Eighteen new laser dyes generating in the visible spectral range

T . Ko tow ski, A . Obzeszko, W . Sk u b isza k, T. Stacewicz

I n s t itu t e o f E x p e r im e n ta l P h y s ic s , W arsaw U n iv e r sity , u l. H o ż a 69, 0 0 -6 8 1 W arszaw a, P o la n d .

J. A. S

ohoka

I n s t itu t e o f F u n d a m e n ta l C h em istry , T ech n ica l U n iv e r sity o f S zczecin , A leja P ia stó w 42, 7 1 -6 5 0 S z c zecin , P o la n d .

The paper presents lasing properties of four series of recently synthetised highly

fluorescent organic dyes. All the investigated dyes are listed in the Table.

Dyes of series A being photostable were synthetised photochemically [1] by

an irradiation of l-phenyl-2-(2-arylethenyl)-3,3-dimethyl-3H-indolium per­

chlorate by a medium pressure mercury lamp. Dyes of series B, C and D were

obtained by non-photochemical methods.

Lasing properties of all the dyes have been investigated in a standard ar­

rangement [2] of a dye laser pumped by a nitrogen laser with 0.25 MW pulses

of 6 ns FWHM time and 55 Hz repetition rate. The laser dye solution was flow­

ing transversely in a compact cell [3]. Since majority of organic glues are not

resistant to the solvents used, our dye cell was sealed with specially developed

inorganic glue [4]. A high dispersion rutile prism [5] served as a tuning elem­

ent. The laser resonator outcoupling was 10 %. The output power was measur­

ed by a sampling oscilloscope (TINITKA OS-1500) with a fast photodiode

corrected for spectrally flat response. Lasing wavelength was measured by

a prismatic spectroscope. Solvents for the dyes were chosen to maximize their

fluorescence. Concentrations of solutions were adjusted to optimize the laser

output power. The optimal concentrations of dyes were measured in optical

density units (i.e., extinction of 1 cm absorption path of the dye solution)

at the pump laser wavelength (337.1 nm). Optical densities given in Table were

extrapolated from the data for the dye solutions diluted to fall within measuring

range of spectrophotometer used (SPECOED UV-VIS). Dyes A1-A8 and

B1-B7 were dissolved in dichloromethane, dyes Cl, C2, Dl, D2 — in xylene.

Figures a-r show absorption and lasing spectra of the dyes. The laser

output power was measured in arbitrary units with 1.0 corresponding to the

maximum output power obtained for Ehodamine 6G in methanol in the same

laser configuration. In the Table for each group a general chemical name and

for every dye the radicals E are given. Fluorescence quantum yields of the

dyes of the group A, measured by means of an HITACHI HFP-4

spectrofluori-D y e _{d e n sity}O p tical L a sin g _{M axim al} pow er F lu o r e ­ scen ce q u a n tu m y ie ld

S u m m ary form ula M eltin g

p o in t [°C] Reraark8 Code R a d ic a l (R )

ô à i

[n m ] ran ge [n m ] m ax [n m ]

5 -R -7 , 7 -d im e th y l-7 H -in d o lo [1 ,2 -a ] q u in o lin u m p erch lo ra te

A I 4 -d ip h e n y l 46.5 5 2 7 -5 6 6 542 0.078 0.881 C ^ H ^ C I N O , 3 0 0 -3 0 1

A 2 4 -m e th o x y p h e n y l 38.0 5 1 6 -5 5 8 528 0.264 0.976 C2BH 22C 10N 5 2 7 1 -2 7 3

A3 4 -m e th y lo p h e n y l 17.5 4 8 3 -5 5 7 508 0.500 0.668 c26h22c i n o4 2 3 4 -2 3 5

A 4 2 -c h lo r o p h e n y l 21 .5 4 8 0 -5 4 9 503 0.333 0.568 c24h1#c i2n o4 2 4 1 -2 4 2

A 5 4 -flu o ro p h en y l 41 .0 4 8 2 -6 6 7 520 1.130 0.612 C ,1H 10C lF N O 1 2 5 4 -2 5 5

A 6 3 -flu o ro p h en y l 10.0 4 8 4 -5 5 8 512 0.848 0.581 C.,i H laC lF N 0 1 2 9 4 -2 9 5

A7 4 -c h lo r o p h e n y l 27.5 4 8 5 -5 7 5 540 0.863 0.581 CMH1BC l1i r o1 2 4 0 -2 4 3 A 8 3 -ch lo ro p h en y l 16.5 4 8 5 -5 5 5 513 0.776 0.546 C24Hi„C12N 0 4 2 3 9 -2 4 1 l- R - 3 , 3 -d im e th y l-3 H -n a p h to [1 ,8 -c d ] p y ry liu m p erch lo ra te B1 3 -m e th y lo s ty r y l 38.5 6 5 5 -7 0 0 645 0.058 -

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Letter to the Editor

269

meter and quinine in 0.1 n H2S04 [6] as the standard are quoted according to

So r o k a

[7]. The melting points of the dyes which serve as a simple evaluation

of their purity are also given.

As it is seen from the presented results the output power of some of the

investigated dyes (e.g. A5, A6, A7) is comparable with Ehodamine 6G. Tun­

ing ranges of all presented dyes are relatively wide. For the dyes B4, B5, B6

and B7 this range exceeds 100 nm. Unfortunately, some of the dyes of the B

group are unstable; for B3 the lasing range could not be even determined.

The decomposition of this dye was manifested by significant changes in the

absorption spectrum.

S p ectra l p ro p erties o f in v e s tig a te d d y e s. D o tte d lin e — a b so rp tio n (A ), so lid lin e — la ser o u tp u t p ow er (L P) in arb itrary u n its n o rm a lized t o m a x im u m p ow er o f K b 6G in m e th a n o l. T h e arrow sh o w s p u m p w a v e le n g th (337.1 nm )

A cknowledgem ents — W e w o u ld lik e to th a n k D r. K . B . S o ro k a an d D r. J . B o g d a ń sk a from

th e I n s t itu t e o f F u n d a m e n ta l C h em istry o f T ech n ica l U n iv e r s ity o f S zczecin for p ro v id in g u s w ith th e d y e s o f group A [9 -1 1 ] an d B [1 2 ], r e s p e c tiv e ly . T h e d y e s o f g ro u p s C an d D w ere s y n th e tis e d b y one o f th e a u th o rs (J .A .S .).

Letter to the Editor

271

References

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[7] Soroka K . B ., D o cto r’s T h esis, T ech n ica l U n iv e r sity o f Szczecin , S zczecin 1987. [8] Da n ie l D . S., He se l t in e D . W ., N ouveaux colorants m ethiniques utiles, en p a rtic u lie r,

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ehinolinow ych, P o lis h p a te n t 121220, 1981.

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ehinolinow ych, P o lish p a te n t 122316, 1982.

[12] Bogdańska J ., D o c to r ’s T h esis, T ech n ical U n iv e r sity of Szczecin, S zczecin 1978.