Phosphorescence is a type of photoluminescence related to fluorescence. Unlike fluorescence, a phosphorescent material does not re-emit the radiation it absorbs; the slower time scales of the re-emission are associated with "forbidden" energy state transitions in quantum mechanics. As these transitions occur slowly in certain materials, absorbed radiation is re-emitted at a lower intensity for up to several hours after the original excitation. Everyday examples of phosphorescent materials are the glow-in-the-dark toys, paint and clock dials that glow after being charged with a bright light such as in any normal reading or room light; the glow fades out, sometimes within a few minutes or up to a few hours in a dark room. Around 1604, Vincenzo Casciarolo discovered a "lapis solaris" near Italy. Once heated in an oxygen-rich furnace, it glowed in the dark; the study of phosphorescent materials led to the discovery of radioactivity in 1896. In simple terms, phosphorescence is a process in which energy absorbed by a substance is released slowly in the form of light.

This is in some cases the mechanism used for "glow-in-the-dark" materials which are "charged" by exposure to light. Unlike the swift reactions in fluorescence, such as those seen in a common fluorescent tube, phosphorescent materials "store" absorbed energy for a longer time, as the processes required to re-emit energy occur less often. Most photoluminescent events, in which a chemical substrate absorbs and re-emits a photon of light, are fast, in the order of 10 nanoseconds. Light is absorbed and emitted at these fast time scales in cases where the energy of the photons involved matches the available energy states and allowed transitions of the substrate. In the special case of phosphorescence, the electron which absorbed the photon undergoes an unusual intersystem crossing into an energy state of higher spin multiplicity a triplet state; as a result, the excited electron can become trapped in the triplet state with only "forbidden" transitions available to return to the lower energy singlet state.

These transitions, although "forbidden", will still occur in quantum mechanics but are kinetically unfavored and thus progress at slower time scales. Most phosphorescent compounds are still fast emitters, with triplet lifetimes in the order of milliseconds. However, some compounds have triplet lifetimes up to minutes or hours, allowing these substances to store light energy in the form of slowly degrading excited electron states. If the phosphorescent quantum yield is high, these substances will release significant amounts of light over long time scales, creating so-called "glow-in-the-dark" materials. S 0 + h ν → S 1 → T 1 → S 0 + h ν ′ where S is a singlet and T a triplet whose subscripts denote states. Transitions can occur to higher energy levels, but the first excited state is denoted for simplicity; some examples of glow-in-the-dark materials do not glow by phosphorescence. For example, glow sticks glow due to a chemiluminescent process, mistaken for phosphorescence. In chemiluminescence, an excited state is created via a chemical reaction.

The light emission tracks the kinetic progress of the underlying chemical reaction. The excited state will transfer to a dye molecule known as a sensitizer or fluorophor, subsequently fluoresce back to the ground state. Common pigments used in phosphorescent materials include strontium aluminate. Use of zinc sulfide for safety related products dates back to the 1930s. However, the development of strontium aluminate, with a luminance 10 times greater than zinc sulfide, has relegated most zinc sulfide based products to the novelty category. Strontium aluminate based pigments are now used in exit signs, pathway marking, other safety related signage. Phosphorescent pigments – zinc sulfide vs. strontium aluminate Phosphorescent Luminous gemstones Luminous paint Microsphere Persistent luminescence Phosphor Phosphoroscope Tritium

Mothers Heaven is the second album from the Scottish rock band Texas. The album was released on 23 September 1991 by Mercury Records; the album spent 4 weeks on the charts. The album saw the release of four singles, the lead single released from Mothers Heaven was entitled "Why Believe in You" which only managed to reach #66 on the UK Singles Charts in September 1991. Follow on single, the alternative rock track, "In My Heart" was released on 14 October 1991 but only managed to reach #74 in the United Kingdom. However, "In My Heart" became Texas's last song to date to chart in the United States, peaking at #14 on the Billboard Hot Rock Tracks chart; the song reached #44 in France. The release of a third single was based on the success of the band in countries such as France and other European countries, as the band's singles were doing poorly in their native United Kingdom; the third single, "Alone with You", saw Texas return to the UK Singles Charts Top 40, peaking at #32. The single continued the success of the band in France, reaching #28.

The fourth and final single, a remix of the title track "Mothers Heaven" was released in 1992, but failed to chart in any countries. After the disappointing performance of singles from the album, the band released a new cover version of the Al Green classic "Tired of Being Alone", which returned them to the UK Top 20; the track was not available on any album until the band's Greatest Hits album released in 2000. Mothers Heaven is the band's lowest charting album in the UK where it remains uncertified, however, it has been certified Gold in both France and Switzerland. AllMusic Guide gave the album three stars out of five, commented: Texas is a good name for this band, whose sound is open and just a bit on the twangy side. Singer Sharleen Spiteri has the perfect voice for this kind of thing: it's low-pitched and dark-hued, is shown off to best effect when she's belting out big, cathartic numbers like the title track and "Why Believe in You." Ally McErlaine is a brilliant slide guitarist who can move from grungy, greasy rock to desolate acoustic Delta blues without missing a beat.

It's true that the group still needs to digest its influences a bit -- "Dream Hotel," in particular, sounds like a U2 reject—but most of the time, Texas does a good job of mapping out its own territory. And this is just their second album. ~ Rick Anderson, All Music Guide All songs written by Johnny McElhone and Sharleen Spiteri except as indicated. "Mothers Heaven" "Why Believe in You" "Dream Hotel" "This Will All Be Mine" "Beliefs" "Alone with You" "In My Heart" "Waiting" "Wrapped in Clothes of Blue" "Return" "Walk the Dust" Recorded at: Park Lane Studios, Glasgow and The Mill Recording Studios, Berkshire. TexasAlly McErlaine - guitar Johnny McElhone - bass Sharleen Spiteri - vocals, guitar Eddie Campbell - keyboards Richard Hynd - drumsOther PersonnelEngineer - George Shilling, Kenny MacDonald, Simon Vinestock Mastered By - Bob Ludwig Producer - Tim Palmer Voice - Stuart Kerr

Lost in Paradise is the 4th album by German band X-Perience. The album includes ten new tracks and three remakes of their greatest hits, "A Neverending Dream", "Circles of Love" and "Magic Fields". "Return to Paradise" was the first single, released in October 2006. The second single was a duet with Midge Ure. With the last single "I Feel Like You", singer Claudia Uhle decided to leave the band. Lost in Paradise was released after a break of six years since their previous album, Journey of Life. After touring and promoting the last album, Polydor/Universal released the promotional single "It's a Sin", a cover of the Pet Shop Boys song; the band took some time off and Claudia released a solo-album under the name Angelzoom in 2005. The album entered the German Album Charts on No. 78. "I Feel Safe" – 3:55 "Return to Paradise" – 3:36 "Personal Heaven" Duet with Midge Ure – 4:01 "Let Me Show You" – 3:47 "I Feel Like You" – 3:30 "Dream of Love" – 3:34 "Million Miles" – 4:09 "Poison Kiss" – 3:48 "Heart of Mine" – 3:34 "Deeper Than Deep" – 3:55 "Circles of Love" Alvarez Album Edit – 3:42 "A Neverending Dream" Alvarez Album Edit – 3:37 "Magic Fields" Alvarez Album Edit – 3:38 Track 1, 4, 5, 6, 7, 8, 10, 11, 12, 13: Written & composed by Matthias Uhle and Alex Kaiser Track 2: Written & composed by Matthias Uhle, Alex Kaiser, Hardy Krech, Mark Nissen Track 3: Written & composed by Midge Ure and Glenn Gregory Track 9: Written & composed by Torben Nielsson and D-Insomniac Track 1, 2, 3, 6 produced and mixed by Elephant Music Track 4, 5, 7, 10 produced and mixed by Hayo Lewerentz & Graham Laybourne at Triggertrax and Boogiepark Studios Track 8 produced and mixed by Koerba for K16 Music at K16 Studio Track 9 produced and mixed by Elephant Music in cooperation with Tone-Kind Track 11, 12, 13 produced and mixed by José Alvarez Brill for www.pleasurepark-studios.com Vocals: Claudia Uhle Track 3: Vocals by Claudia Uhle and Midge Ure Track 1, 3, 9: Guitars by Mark Nissen Track 10: Guitars by Graham Laybourne Track 11, 12, 13: Additional keyboard/production by Henning Verlage Track 13: Additional guitar by José Alvarez Brill "Fireworks" – released as b-side on single "Personal Heaven" "Step Into the Light" – released as b-side on single "I Feel Like You" "Lay Down Your Guns" – outtake of album Journey Of Life, recorded 1999, released as b-side on single "I Feel Like You" There exist plenty of demo and alternate versions of the album tracks.

Many songs were edited and/or re-written during the three years of creating the album. Some of these versions were released on x-perience.de. For a limited time, these songs were free downloads: "Deeper Than Deep" "Let Me Show You" "Million Miles" "Million Miles" "Poison Kiss""Dream to Me" is the name of a demo version of I Feel Like You; the song Joining Together is based on the same melody as Million Miles. Joining Together was limited released as Image-song for Böllhoff, a provider of fastening and systems technology. Dragonfly is an unreleased song, only played live during concerts 2003–2005. In 2003, there were plans to include cover-versions of It's A Sin and Moonlight Shadow because they played these songs live but this was scrapped